diff --git a/.babelrc b/.babelrc
index 376b4a8264..c6c0b2e3aa 100644
--- a/.babelrc
+++ b/.babelrc
@@ -9,6 +9,7 @@
     "chrome/content/zotero/xpcom/citeproc.js",
     "resource/react.js",
     "resource/react-dom.js",
+    "resource/react-virtualized.js",
     "test/resource/*.js"
   ],
   "plugins": [
diff --git a/chrome/content/zotero/components/search.jsx b/chrome/content/zotero/components/search.jsx
index 872d301da3..5e448afbfe 100644
--- a/chrome/content/zotero/components/search.jsx
+++ b/chrome/content/zotero/components/search.jsx
@@ -54,17 +54,17 @@ class Search extends React.PureComponent {
 	}
 	
 	focus() {
-		this.inputRef.focus();
+		this.inputRef.current.focus();
 	}
 	
 	render() {
 		return (
 			<div className="search">
 				<input
+					ref={this.inputRef}
 					type="search"
 					onChange={this.handleChange}
 					onKeyDown={this.handleKeyDown}
-					ref={this.inputRef}
 					value={this.state.immediateValue}
 				/>
 				{this.state.immediateValue !== ''
diff --git a/chrome/content/zotero/components/tag-selector.jsx b/chrome/content/zotero/components/tag-selector.jsx
index bf415fa671..55287e3c34 100644
--- a/chrome/content/zotero/components/tag-selector.jsx
+++ b/chrome/content/zotero/components/tag-selector.jsx
@@ -3,21 +3,30 @@
 const React = require('react');
 const PropTypes = require('prop-types');
 const TagList = require('./tag-selector/tag-list');
-const Input = require('./form/input');
 const { Button } = require('./button');
 const { IconTagSelectorMenu } = require('./icons');
 const Search = require('./search');
 
-class TagSelector extends React.Component {
+class TagSelector extends React.PureComponent {
 	render() {
 		return (
 			<div className="tag-selector">
-				<TagList {...this.props} />
+				<TagList
+					ref={this.props.tagListRef}
+					tags={this.props.tags}
+					dragObserver={this.props.dragObserver}
+					onSelect={this.props.onSelect}
+					onTagContext={this.props.onTagContext}
+					loaded={this.props.loaded}
+					width={this.props.width}
+					height={this.props.height}
+					fontSize={this.props.fontSize}
+				/>
 				<div className="tag-selector-filter-container">
 					<Search
+						ref={this.props.searchBoxRef}
 						value={this.props.searchString}
 						onSearch={this.props.onSearch}
-						inputRef={this.searchBoxRef}
 						className="tag-selector-filter"
 					/>
 					<Button
@@ -34,24 +43,34 @@ class TagSelector extends React.Component {
 }
 
 TagSelector.propTypes = {
+	// TagList
+	tagListRef: PropTypes.object,
 	tags: PropTypes.arrayOf(PropTypes.shape({
 		name: PropTypes.string,
 		selected: PropTypes.bool,
 		color: PropTypes.string,
-		disabled: PropTypes.bool
+		disabled: PropTypes.bool,
+		width: PropTypes.number
 	})),
 	dragObserver: PropTypes.shape({
 		onDragOver: PropTypes.func,
 		onDragExit: PropTypes.func,
 		onDrop: PropTypes.func
 	}),
-	searchBoxRef: PropTypes.object,
-	searchString: PropTypes.string,
 	onSelect: PropTypes.func,
 	onTagContext: PropTypes.func,
-	onSearch: PropTypes.func,
-	onSettings: PropTypes.func,
 	loaded: PropTypes.bool,
+	width: PropTypes.number.isRequired,
+	height: PropTypes.number.isRequired,
+	fontSize: PropTypes.number.isRequired,
+	
+	// Search
+	searchBoxRef: PropTypes.object,
+	searchString: PropTypes.string,
+	onSearch: PropTypes.func,
+	
+	// Button
+	onSettings: PropTypes.func,
 };
 
 TagSelector.defaultProps = {
diff --git a/chrome/content/zotero/components/tag-selector/tag-list.jsx b/chrome/content/zotero/components/tag-selector/tag-list.jsx
index ba140c85eb..7fc3666ed6 100644
--- a/chrome/content/zotero/components/tag-selector/tag-list.jsx
+++ b/chrome/content/zotero/components/tag-selector/tag-list.jsx
@@ -1,23 +1,123 @@
 const React = require('react');
-const { FormattedMessage } = require('react-intl');
 const PropTypes = require('prop-types');
-const cx = require('classnames');
+const { FormattedMessage } = require('react-intl');
+var { Collection } = require('react-virtualized');
+
+var filterBarHeight = 32;
+var tagPaddingTop = 4;
+var tagPaddingLeft = 2;
+var tagPaddingRight = 2;
+var tagPaddingBottom = 4;
+var tagSpaceBetweenX = 7;
+var tagSpaceBetweenY = 4;
+var panePaddingTop = 2;
+var panePaddingLeft = 2;
+var panePaddingRight = 25;
+//var panePaddingBottom = 2;
+var minHorizontalPadding = panePaddingLeft + tagPaddingLeft + tagPaddingRight + panePaddingRight;
 
 class TagList extends React.PureComponent {
-	renderTag(index) {
-		const { tags } = this.props;
-		const tag = index < tags.length ?
-			tags[index] : {
-				tag: "",
-			};
+	constructor(props) {
+		super(props);
+		this.collectionRef = React.createRef();
+		this.scrollToTopOnNextUpdate = false;
+		this.prevTagCount = 0;
+	}
+	
+	componentDidUpdate(prevProps) {
+		// Redraw all tags on every refresh
+		if (this.collectionRef && this.collectionRef.current) {
+			// If width or height changed, recompute positions. It seems like this should happen
+			// automatically, but it doesn't as of 9.21.0.
+			if (prevProps.height != this.props.height
+					|| prevProps.width != this.props.width
+					|| prevProps.fontSize != this.props.fontSize
+					|| prevProps.tags != this.props.tags) {
+				this.collectionRef.current.recomputeCellSizesAndPositions();
+			}
+			// If dimensions didn't change, just redraw at current positions. Without this, clicking
+			// on a tag that doesn't change the tag count (as when clicking on a second tag in an
+			// already filtered list) doesn't update the tag's selection state.
+			else {
+				this.collectionRef.current.forceUpdate();
+			}
+		}
+		
+		if (this.scrollToTopOnNextUpdate && this.collectionRef.current) {
+			this.scrollToTop();
+			this.scrollToTopOnNextUpdate = false;
+		}
+	}
+	
+	scrollToTop() {
+		if (!this.collectionRef.current) return;
+		// Scroll to the top of the view
+		document.querySelector('.tag-selector-list').scrollTop = 0;
+		// Reset internal component scroll state to force it to redraw components, since that
+		// doesn't seem to happen automatically as of 9.21.0. Without this, scrolling down and
+		// clicking on a tag blanks out the pane (presumably because it still thinks it's at an
+		// offset where no tags exist).
+		if (this.collectionRef.current._collectionView) {
+			this.collectionRef.current._collectionView._setScrollPosition({
+				scrollLeft: 0,
+				scrollTop: 0
+			});
+		}
+	}
+	
+	/**
+	 * Calculate the x,y coordinates of all tags
+	 */
+	updatePositions() {
+		var tagMaxWidth = this.props.width - minHorizontalPadding;
+		var rowHeight = tagPaddingTop + this.props.fontSize + tagPaddingBottom + tagSpaceBetweenY;
+		var positions = [];
+		var row = 0;
+		let rowX = panePaddingLeft;
+		for (let i = 0; i < this.props.tags.length; i++) {
+			let tag = this.props.tags[i];
+			let tagWidth = tagPaddingLeft + Math.min(tag.width, tagMaxWidth) + tagPaddingRight;
+			// If cell fits, add to current row
+			if ((rowX + tagWidth) < (this.props.width - panePaddingLeft - panePaddingRight)) {
+				positions[i] = [rowX, panePaddingTop + (row * rowHeight)];
+			}
+			// Otherwise, start new row
+			else {
+				row++;
+				rowX = panePaddingLeft;
+				positions[i] = [rowX, panePaddingTop + (row * rowHeight)];
+			}
+			rowX += tagWidth + tagSpaceBetweenX;
+		}
+		this.positions = positions;
+	}
+	
+	cellSizeAndPositionGetter = ({ index }) => {
+		var tagMaxWidth = this.props.width - minHorizontalPadding;
+		return {
+			width: Math.min(this.props.tags[index].width, tagMaxWidth),
+			height: this.props.fontSize,
+			x: this.positions[index][0],
+			y: this.positions[index][1]
+		};
+	}
+	
+	renderTag = ({ index, _key, style }) => {
+		var tag = this.props.tags[index];
+		
 		const { onDragOver, onDragExit, onDrop } = this.props.dragObserver;
-
-		const className = cx('tag-selector-item', 'zotero-clicky', {
-			selected: tag.selected,
-			colored: tag.color,
-			disabled: tag.disabled
-		});
-
+		
+		var className = 'tag-selector-item zotero-clicky';
+		if (tag.selected) {
+			className += ' selected';
+		}
+		if (tag.color) {
+			className += ' colored';
+		}
+		if (tag.disabled) {
+			className += ' disabled';
+		}
+		
 		let props = {
 			className,
 			onClick: ev => !tag.disabled && this.props.onSelect(tag.name, ev),
@@ -26,52 +126,89 @@ class TagList extends React.PureComponent {
 			onDragExit,
 			onDrop
 		};
-
+		
+		props.style = {
+			...style
+		};
+		
 		if (tag.color) {
-			props['style'] = {
-				color: tag.color,
-			};
+			props.style.color = tag.color;
 		}
-
-
+		
 		return (
-			<li key={index} {...props}>
+			<div key={tag.name} {...props}>
 				{tag.name}
-			</li>
+			</div>
 		);
 	}
-
+	
 	render() {
-		const totalTagCount = this.props.tags.length;
-		var tagList = (
-			<ul className="tag-selector-list">
-				{
-					[...Array(totalTagCount).keys()].map(index => this.renderTag(index))
-				}
-			</ul>
-		);
+		Zotero.debug("Rendering tag list");
+		const tagCount = this.props.tags.length;
+		
+		var tagList;
 		if (!this.props.loaded) {
 			tagList = (
 				<div className="tag-selector-message">
 					<FormattedMessage id="zotero.tagSelector.loadingTags" />
 				</div>
 			);
-		} else if (totalTagCount == 0) {
+		}
+		else if (tagCount == 0) {
 			tagList = (
 				<div className="tag-selector-message">
 					<FormattedMessage id="zotero.tagSelector.noTagsToDisplay" />
 				</div>
 			);
 		}
+		else {
+			// Scroll to top if more than one tag was removed
+			if (tagCount < this.prevTagCount - 1) {
+				this.scrollToTopOnNextUpdate = true;
+			}
+			this.prevTagCount = tagCount;
+			this.updatePositions();
+			tagList = (
+				<Collection
+					ref={this.collectionRef}
+					className="tag-selector-list"
+					cellCount={tagCount}
+					cellRenderer={this.renderTag}
+					cellSizeAndPositionGetter={this.cellSizeAndPositionGetter}
+					verticalOverscanSize={300}
+					width={this.props.width}
+					height={this.props.height - filterBarHeight}
+				/>
+			);
+		}
+		
 		return (
-			<div
-				className="tag-selector-container"
-				ref={ref => { this.container = ref }}>
+			<div className="tag-selector-list-container">
 				{tagList}
 			</div>
-		)
-
+		);
 	}
+	
+	static propTypes = {
+		tags: PropTypes.arrayOf(PropTypes.shape({
+			name: PropTypes.string,
+			selected: PropTypes.bool,
+			color: PropTypes.string,
+			disabled: PropTypes.bool,
+			width: PropTypes.number
+		})),
+		dragObserver: PropTypes.shape({
+			onDragOver: PropTypes.func,
+			onDragExit: PropTypes.func,
+			onDrop: PropTypes.func
+		}),
+		onSelect: PropTypes.func,
+		onTagContext: PropTypes.func,
+		loaded: PropTypes.bool,
+		width: PropTypes.number.isRequired,
+		height: PropTypes.number.isRequired,
+		fontSize: PropTypes.number.isRequired,
+	};
 }
 
 module.exports = TagList;
diff --git a/chrome/content/zotero/containers/tagSelector.jsx b/chrome/content/zotero/containers/tagSelector.jsx
index 26f5983f5b..8604429a44 100644
--- a/chrome/content/zotero/containers/tagSelector.jsx
+++ b/chrome/content/zotero/containers/tagSelector.jsx
@@ -1,24 +1,22 @@
 /* global Zotero: false */
 'use strict';
 
-(function() {
-
 const React = require('react');
 const ReactDOM = require('react-dom');
+const PropTypes = require('prop-types');
 const { IntlProvider } = require('react-intl');
 const TagSelector = require('components/tag-selector.js');
-const noop = Promise.resolve();
 const defaults = {
 	tagColors: new Map(),
 	tags: [],
+	scope: null,
 	showAutomatic: Zotero.Prefs.get('tagSelector.showAutomatic'),
 	searchString: '',
-	inScope: new Set(),
 	loaded: false
 };
 const { Cc, Ci } = require('chrome');
 
-Zotero.TagSelector = class TagSelectorContainer extends React.Component {
+Zotero.TagSelector = class TagSelectorContainer extends React.PureComponent {
 	constructor(props) {
 		super(props);
 		this._notifierID = Zotero.Notifier.registerObserver(
@@ -26,31 +24,57 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 			['collection-item', 'item', 'item-tag', 'tag', 'setting'],
 			'tagSelector'
 		);
-		this.displayAllTags = Zotero.Prefs.get('tagSelector.displayAllTags');
-		this.selectedTags = new Set();
-		this.state = defaults;
+		Zotero.Prefs.registerObserver('fontSize', this.handleFontChange.bind(this));
+		
+		this.tagListRef = React.createRef();
 		this.searchBoxRef = React.createRef();
+		
+		this.displayAllTags = Zotero.Prefs.get('tagSelector.displayAllTags');
+		// Not stored in state to avoid an unnecessary refresh. Instead, when a tag is selected, we
+		// trigger the selection handler, which updates the visible items, which triggers
+		// onItemViewChanged(), which triggers a refresh with the new tags.
+		this.selectedTags = new Set();
+		this.widths = new Map();
+		this.widthsBold = new Map();
+		
+		this.state = {
+			...defaults,
+			...this.getContainerDimensions(),
+			...this.getFontInfo()
+		};
 	}
 	
 	focusTextbox() {
-		this.searchBoxRef.focus();
+		this.searchBoxRef.current.focus();
+	}
+	
+	componentDidUpdate(_prevProps, _prevState) {
+		Zotero.debug("Tag selector updated");
+		
+		// If we changed collections, scroll to top
+		if (this.collectionTreeRow && this.collectionTreeRow.id != this.prevTreeViewID) {
+			this.tagListRef.current.scrollToTop();
+			this.prevTreeViewID = this.collectionTreeRow.id;
+		}
 	}
 	
 	// Update trigger #1 (triggered by ZoteroPane)
-	async onItemViewChanged({collectionTreeRow, libraryID, tagsInScope}) {
+	async onItemViewChanged({ collectionTreeRow, libraryID }) {
 		Zotero.debug('Updating tag selector from current view');
 		
-		this.collectionTreeRow = collectionTreeRow || this.collectionTreeRow;
-		
-		let newState = {loaded: true};
-		
-		if (!this.state.tagColors.length && libraryID && this.libraryID != libraryID) {
-			newState.tagColors = Zotero.Tags.getColors(libraryID);
-		}
+		var prevLibraryID = this.libraryID;
+		this.collectionTreeRow = collectionTreeRow;
 		this.libraryID = libraryID;
 		
-		newState.tags = await this.getTags(tagsInScope,
-			this.state.tagColors.length ? this.state.tagColors : newState.tagColors);
+		var newState = {
+			loaded: true
+		};
+		if (prevLibraryID != libraryID) {
+			newState.tagColors = Zotero.Tags.getColors(libraryID);
+		}
+		var { tags, scope } = await this.getTagsAndScope();
+		newState.tags = tags;
+		newState.scope = scope;
 		this.setState(newState);
 	}
 	
@@ -59,13 +83,13 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 		if (type === 'setting') {
 			if (ids.some(val => val.split('/')[1] == 'tagColors')) {
 				Zotero.debug("Updating tag selector after tag color change");
-				let tagColors = Zotero.Tags.getColors(this.libraryID);
-				this.state.tagColors = tagColors;
-				this.setState({tagColors, tags: await this.getTags(null, tagColors)});
+				this.setState({
+					tagColors: Zotero.Tags.getColors(this.libraryID)
+				});
 			}
 			return;
 		}
-			
+		
 		// Ignore anything other than deletes in duplicates view
 		if (this.collectionTreeRow && this.collectionTreeRow.isDuplicates()) {
 			switch (event) {
@@ -83,107 +107,346 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 			return;
 		}
 		
-		// If a selected tag no longer exists, deselect it
-		if (type == 'tag' && (event == 'modify' || event == 'delete')) {
-			let changed = false;
-			for (let id of ids) {
-				let tag = extraData[id].old.tag;
-				if (this.selectedTags.has(tag)) {
-					this.selectedTags.delete(tag);
-					changed = true;
-				}
-			}
-			if (changed && typeof(this.props.onSelection) === 'function') {
-				this.props.onSelection(this.selectedTags);
-			}
+		// Ignore tag deletions, which are handled by 'item-tag' 'remove'
+		if (type == 'tag') {
 			return;
 		}
 		
-		// TODO: Check libraryID for some events to avoid refreshing unnecessarily on sync changes?
-		
 		Zotero.debug("Updating tag selector after tag change");
-		var newTags = await this.getTags();
 		
-		if (type == 'item-tag' && event == 'remove') {
-			let changed = false;
-			let visibleTags = newTags.map(tag => tag.tag);
+		if (type == 'item-tag' && ['add', 'remove'].includes(event)) {
+			let changedTagsInScope = [];
+			let changedTagsInView = [];
+			// Group tags by tag type for lookup
+			let tagsByType = new Map();
 			for (let id of ids) {
-				let tag = extraData[id].tag;
-				if (this.selectedTags.has(tag) && !visibleTags.includes(tag)) {
-					this.selectedTags.delete(tag);
-					changed = true;
+				let [_, tagID] = id.split('-');
+				let type = extraData[id].type;
+				let typeTags = tagsByType.get(type);
+				if (!typeTags) {
+					typeTags = [];
+					tagsByType.set(type, typeTags);
+				}
+				typeTags.push(parseInt(tagID));
+			}
+			// Check tags for each tag type to see if they're in view/scope
+			for (let [type, tagIDs] of tagsByType) {
+				changedTagsInScope.push(...await this.collectionTreeRow.getTags([type], tagIDs));
+				if (this.displayAllTags) {
+					changedTagsInView.push(
+						...await Zotero.Tags.getAllWithin({ libraryID: this.libraryID, tagIDs })
+					);
 				}
 			}
-			if (changed && typeof(this.props.onSelection) === 'function') {
-				this.props.onSelection(this.selectedTags);
+			if (!this.displayAllTags) {
+				changedTagsInView = changedTagsInScope;
+			}
+			changedTagsInScope = new Set(changedTagsInScope.map(tag => tag.tag));
+			
+			if (event == 'add') {
+				this.sortTags(changedTagsInView);
+				if (!changedTagsInView.length) {
+					return;
+				}
+				this.setState((state, _props) => {
+					// Insert sorted
+					var newTags = [...state.tags];
+					var newScope = state.scope ? new Set(state.scope) : new Set();
+					var scopeChanged = false;
+					var start = 0;
+					var collation = Zotero.getLocaleCollation();
+					for (let tag of changedTagsInView) {
+						let name = tag.tag;
+						let added = false;
+						for (let i = start; i < newTags.length; i++) {
+							start++;
+							let cmp = collation.compareString(1, newTags[i].tag, name);
+							// Skip tag if it already exists
+							if (cmp == 0) {
+								added = true;
+								break;
+							}
+							if (cmp > 0) {
+								newTags.splice(i, 0, tag);
+								added = true;
+								break;
+							}
+						}
+						if (!added) {
+							newTags.push(tag);
+						}
+						
+						if (changedTagsInScope.has(name) && !newScope.has(name)) {
+							newScope.add(name);
+							scopeChanged = true;
+						}
+					}
+					
+					var newState = {
+						tags: newTags
+					};
+					if (scopeChanged) {
+						newState.scope = newScope;
+					}
+					return newState;
+				});
+				return;
+			}
+			else if (event == 'remove') {
+				changedTagsInView = new Set(changedTagsInView.map(tag => tag.tag));
+				
+				this.setState((state, props) => {
+					var previousTags = new Set(state.tags.map(tag => tag.tag));
+					var tagsToRemove = new Set();
+					var newScope;
+					var selectionChanged = false;
+					for (let id of ids) {
+						let name = extraData[id].tag;
+						let removed = false;
+						
+						// If tag was shown previously and shouldn't be anymore, remove from view
+						if (previousTags.has(name) && !changedTagsInView.has(name)) {
+							tagsToRemove.add(name);
+							removed = true;
+						}
+						
+						// Remove from scope if there is one
+						if (state.scope && state.scope.has(name) && !changedTagsInScope.has(name)) {
+							if (!newScope) {
+								newScope = new Set(state.scope);
+							}
+							newScope.delete(name);
+							removed = true;
+						}
+						
+						// Removed from either view or scope
+						if (removed) {
+							// Deselect if selected
+							if (this.selectedTags.has(name)) {
+								this.selectedTags.delete(name);
+								selectionChanged = true;
+							}
+							
+							// If removing a tag from view, clear its cached width. It might still
+							// be in this or another library, but if so we'll just recalculate its
+							// width the next time it's needed.
+							this.widths.delete(name);
+							this.widthsBold.delete(name);
+						}
+					}
+					if (selectionChanged && typeof props.onSelection == 'function') {
+						props.onSelection(this.selectedTags);
+					}
+					var newState = {};
+					if (tagsToRemove.size) {
+						newState.tags = state.tags.filter(tag => !tagsToRemove.has(tag.tag));
+					}
+					if (newScope) {
+						newState.scope = newScope;
+					}
+					return newState;
+				});
+				return;
 			}
 		}
 		
-		return this.setState({tags: newTags});
+		this.setState(await this.getTagsAndScope());
 	}
 	
-	async getTags(tagsInScope, tagColors) {
-		if (!tagsInScope) {
-			tagsInScope = await this.collectionTreeRow.getChildTags();
-		}
-		this.inScope = new Set(tagsInScope.map(t => t.tag));
-		let tags;
+	async getTagsAndScope() {
+		var tags = await this.collectionTreeRow.getTags();
+		// The scope is all visible tags, not all tags in the library
+		var scope = new Set(tags.map(t => t.tag));
 		if (this.displayAllTags) {
-			tags = await Zotero.Tags.getAll(this.libraryID, [0, 1]);
-		} else {
-			tags = tagsInScope
+			tags = await Zotero.Tags.getAll(this.libraryID);
 		}
 		
-		tagColors = tagColors || this.state.tagColors;
-			
-		// Add colored tags that aren't already real tags
-		let regularTags = new Set(tags.map(tag => tag.tag));
-		let coloredTags = Array.from(tagColors.keys());
-
-		coloredTags.filter(ct => !regularTags.has(ct)).forEach(x =>
-			tags.push(Zotero.Tags.cleanData({ tag: x }))
-		);
-			
-		// Sort by name (except for colored tags, which sort by assigned number key)
-		tags.sort(function (a, b) {
-			let aColored = tagColors.get(a.tag);
-			let bColored = tagColors.get(b.tag);
-			if (aColored && !bColored) return -1;
-			if (!aColored && bColored) return 1;
-			if (aColored && bColored) {
-				return aColored.position - bColored.position;
+		// If tags haven't changed, return previous array without sorting again
+		if (this.state.tags.length == tags.length) {
+			let prevTags = new Set(this.state.tags.map(tag => tag.tag));
+			let same = true;
+			for (let tag of tags) {
+				if (!prevTags.has(tag.tag)) {
+					same = false;
+					break;
+				}
 			}
-			
-			return Zotero.getLocaleCollation().compareString(1, a.tag, b.tag);
-		});
+			if (same) {
+				Zotero.debug("Tags haven't changed");
+				return {
+					tags: this.state.tags,
+					scope
+				};
+			}
+		}
 		
-		return tags;
+		this.sortTags(tags);
+		return { tags, scope };
 	}
-
+	
+	sortTags(tags) {
+		var d = new Date();
+		var collation = Zotero.Intl.collation;
+		tags.sort(function (a, b) {
+			return collation.compareString(1, a.tag, b.tag);
+		});
+		Zotero.debug(`Sorted tags in ${new Date() - d} ms`);
+	}
+	
+	getContainerDimensions() {
+		var container = document.getElementById(this.props.container);
+		return {
+			width: container.clientWidth,
+			height: container.clientHeight
+		};
+	}
+	
+	handleResize() {
+		//Zotero.debug("Resizing tag selector");
+		var { width, height } = this.getContainerDimensions();
+		this.setState({ width, height });
+	}
+	
+	getFontInfo() {
+		var elem = document.createElementNS("http://www.w3.org/1999/xhtml", "div");
+		elem.className = 'tag-selector-item';
+		elem.style.position = 'absolute';
+		elem.style.opacity = 0;
+		var container = document.getElementById(this.props.container);
+		container.appendChild(elem);
+		var style = window.getComputedStyle(elem);
+		var props = {
+			fontSize: style.getPropertyValue('font-size'),
+			fontFamily: style.getPropertyValue('font-family')
+		};
+		container.removeChild(elem);
+		return props;
+	}
+	
+	/**
+	 * Recompute tag widths based on the current font settings
+	 */
+	handleFontChange() {
+		this.widths.clear();
+		this.widthsBold.clear();
+		this.setState({
+			...this.getFontInfo()
+		});
+	}
+	
+	/**
+	 * Uses canvas.measureText to compute and return the width of the given text of given font in pixels.
+	 *
+	 * @param {String} text The text to be rendered.
+	 * @param {String} font The css font descriptor that text is to be rendered with (e.g. "bold 14px verdana").
+	 *
+	 * @see https://stackoverflow.com/questions/118241/calculate-text-width-with-javascript/21015393#21015393
+	 */
+	getTextWidth(text, font) {
+		// re-use canvas object for better performance
+		var canvas = this.canvas || (this.canvas = document.createElementNS("http://www.w3.org/1999/xhtml", "canvas"));
+		var context = canvas.getContext("2d");
+		context.font = font;
+		// Add a little more to make sure we don't crop
+		var metrics = context.measureText(text);
+		return Math.ceil(metrics.width);
+	}
+	
+	getWidth(name) {
+		var num = 0;
+		var font = this.state.fontSize + ' ' + this.state.fontFamily;
+		// Colored tags are shown in bold, which results in a different width
+		var fontBold = 'bold ' + font;
+		let hasColor = this.state.tagColors.has(name);
+		let widths = hasColor ? this.widthsBold : this.widths;
+		let width = widths.get(name);
+		if (width === undefined) {
+			//Zotero.debug(`Calculating ${hasColor ? 'bold ' : ''}width for tag '${name}'`);
+			width = this.getTextWidth(name, hasColor ? fontBold : font);
+			widths.set(name, width);
+		}
+		return width;
+	}
+	
 	render() {
-		let tags = this.state.tags;
+		Zotero.debug("Rendering tag selector");
+		var tags = this.state.tags;
+		var tagColors = this.state.tagColors;
+		
 		if (!this.state.showAutomatic) {
-			tags = tags.filter(t => t.type != 1).map(t => t.tag);
+			tags = tags.filter(t => t.type != 1);
 		}
 		// Remove duplicates from auto and manual tags
 		else {
-			tags = Array.from(new Set(tags.map(t => t.tag)));
+			let seen = new Set();
+			let newTags = [];
+			for (let tag of tags) {
+				if (!seen.has(tag.tag)) {
+					newTags.push(tag);
+					seen.add(tag.tag);
+				}
+			}
+			tags = newTags;
 		}
+		
+		// Extract colored tags
+		var coloredTags = [];
+		for (let i = 0; i < tags.length; i++) {
+			if (tagColors.has(tags[i].tag)) {
+				coloredTags.push(...tags.splice(i, 1));
+				i--;
+			}
+		}
+		
+		// Add colored tags that aren't already real tags
+		var extractedColoredTags = new Set(coloredTags.map(tag => tag.tag));
+		[...tagColors.keys()]
+			.filter(tag => !extractedColoredTags.has(tag))
+			.forEach(tag => coloredTags.push(Zotero.Tags.cleanData({ tag })));
+		
+		// Sort colored tags and place at beginning
+		coloredTags.sort((a, b) => {
+			return tagColors.get(a.tag).position - tagColors.get(b.tag).position;
+		});
+		tags = coloredTags.concat(tags);
+		
+		// Filter
 		if (this.state.searchString) {
 			let lcStr = this.state.searchString.toLowerCase();
-			tags = tags.filter(tag => tag.toLowerCase().includes(lcStr));
+			tags = tags.filter(tag => tag.tag.toLowerCase().includes(lcStr));
 		}
-		tags = tags.map((name) => {
-			return {
+		
+		// Prepare tag objects for list component
+		//var d = new Date();
+		var inTagColors = true;
+		tags = tags.map((tag) => {
+			let name = tag.tag;
+			tag = {
 				name,
-				selected: this.selectedTags.has(name),
-				color: this.state.tagColors.has(name) ? this.state.tagColors.get(name).color : '',
-				disabled: !this.inScope.has(name)
+				width: tag.width
+			};
+			if (this.selectedTags.has(name)) {
+				tag.selected = true;
 			}
-		});	
+			if (inTagColors && tagColors.has(name)) {
+				tag.color = tagColors.get(name).color;
+			}
+			else {
+				inTagColors = false;
+			}
+			// If we're not displaying all tags, we only need to check the scope for colored tags,
+			// since everything else will be in scope
+			if ((this.displayAllTags || inTagColors) && !this.state.scope.has(name)) {
+				tag.disabled = true;
+			}
+			tag.width = this.getWidth(name);
+			return tag;
+		});
+		//Zotero.debug(`Prepared tags in ${new Date() - d} ms`);
 		return <TagSelector
 			tags={tags}
 			searchBoxRef={this.searchBoxRef}
+			tagListRef={this.tagListRef}
 			searchString={this.state.searchString}
 			dragObserver={this.dragObserver}
 			onSelect={this.state.viewOnly ? () => {} : this.handleTagSelected}
@@ -191,6 +454,9 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 			onSearch={this.handleSearch}
 			onSettings={this.handleSettings.bind(this)}
 			loaded={this.state.loaded}
+			width={this.state.width}
+			height={this.state.height}
+			fontSize={parseInt(this.state.fontSize.replace('px', ''))}
 		/>;
 	}
 
@@ -198,13 +464,6 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 		this.state.viewOnly != (mode == 'view') && this.setState({viewOnly: mode == 'view'});
 	}
 
-	uninit() {
-		ReactDOM.unmountComponentAtNode(this.domEl);
-		if (this._notifierID) {
-			Zotero.Notifier.unregisterObserver(this._notifierID);
-		}
-	}
-
 	handleTagContext = (tag, ev) => {
 		let tagContextMenu = document.getElementById('tag-menu');
 		ev.preventDefault();
@@ -244,7 +503,7 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 			var elem = event.target;
 			
 			// Ignore drops not on tags
-			if (elem.localName != 'li') {
+			if (!elem.classList.contains('tag-selector-item')) {
 				return;
 			}
 			
@@ -262,7 +521,7 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 			var elem = event.target;
 			
 			// Ignore drops not on tags
-			if (elem.localName != 'li') {
+			if (!elem.classList.contains('tag-selector-item')) {
 				return;
 			}
 
@@ -346,8 +605,8 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 		
 		let selectedTags = this.selectedTags;
 		if (selectedTags.has(this.contextTag.name)) {
-			var wasSelected = true;
 			selectedTags.delete(this.contextTag.name);
+			selectedTags.add(newName.value);
 		}
 		
 		if (Zotero.Tags.getID(this.contextTag.name)) {
@@ -363,11 +622,6 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 			await Zotero.Tags.setColor(this.libraryID, this.contextTag.name, false);
 			await Zotero.Tags.setColor(this.libraryID, newName.value, color.color);
 		}
-		
-		if (wasSelected) {
-			selectedTags.add(newName.value);
-		}
-		this.setState({tags: await this.getTags()})
 	}
 
 	async openDeletePrompt() {
@@ -391,15 +645,13 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 		else {
 			await Zotero.Tags.setColor(this.libraryID, this.contextTag.name, false);
 		}
-
-		this.setState({tags: await this.getTags()});
 	}
 
 	async toggleDisplayAllTags(newValue) {
 		newValue = typeof(newValue) === 'undefined' ? !this.displayAllTags : newValue;
 		Zotero.Prefs.set('tagSelector.displayAllTags', newValue);
 		this.displayAllTags = newValue;
-		this.setState({tags: await this.getTags()});
+		this.setState(await this.getTagsAndScope());
 	}
 
 	toggleShowAutomatic(newValue) {
@@ -474,5 +726,19 @@ Zotero.TagSelector = class TagSelectorContainer extends React.Component {
 		ref.domEl = domEl;
 		return ref;
 	}
-}
-})();
+	
+	uninit() {
+		ReactDOM.unmountComponentAtNode(this.domEl);
+		if (this._notifierID) {
+			Zotero.Notifier.unregisterObserver(this._notifierID);
+		}
+		if (this._prefObserverID) {
+			Zotero.Prefs.unregisterObserver('fontSize', this.handleFontChange.bind(this));
+		}
+	}
+	
+	static propTypes = {
+		container: PropTypes.string.isRequired,
+		onSelection: PropTypes.func.isRequired,
+	};
+};
diff --git a/chrome/content/zotero/xpcom/collectionTreeRow.js b/chrome/content/zotero/xpcom/collectionTreeRow.js
index 07068df974..d86bc5ab27 100644
--- a/chrome/content/zotero/xpcom/collectionTreeRow.js
+++ b/chrome/content/zotero/xpcom/collectionTreeRow.js
@@ -366,13 +366,17 @@ Zotero.CollectionTreeRow.prototype.getSearchObject = Zotero.Promise.coroutine(fu
 	return s2;
 });
 
+Zotero.CollectionTreeRow.prototype.getChildTags = function () {
+	Zotero.warn("Zotero.CollectionTreeRow::getChildTags() is deprecated -- use getTags() instead");
+	return this.getTags();
+};
 
 /**
  * Returns all the tags used by items in the current view
  *
  * @return {Promise<Object[]>}
  */
-Zotero.CollectionTreeRow.prototype.getChildTags = Zotero.Promise.coroutine(function* () {
+Zotero.CollectionTreeRow.prototype.getTags = async function (types, tagIDs) {
 	switch (this.type) {
 		// TODO: implement?
 		case 'share':
@@ -381,9 +385,9 @@ Zotero.CollectionTreeRow.prototype.getChildTags = Zotero.Promise.coroutine(funct
 		case 'bucket':
 			return [];
 	}
-	var results = yield this.getSearchResults(true);
-	return Zotero.Tags.getAllWithinSearchResults(results);
-});
+	var results = await this.getSearchResults(true);
+	return Zotero.Tags.getAllWithin({ tmpTable: results, types, tagIDs });
+};
 
 
 Zotero.CollectionTreeRow.prototype.setSearch = function (searchText) {
diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index 6880bf5997..1a8932606a 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -1794,12 +1794,14 @@ Zotero.Item.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 			for (let i=0; i<toRemove.length; i++) {
 				let tag = toRemove[i];
 				let tagID = Zotero.Tags.getID(tag.tag);
+				let tagType = tag.type ? tag.type : 0;
 				let sql = "DELETE FROM itemTags WHERE itemID=? AND tagID=? AND type=?";
-				yield Zotero.DB.queryAsync(sql, [this.id, tagID, tag.type ? tag.type : 0]);
+				yield Zotero.DB.queryAsync(sql, [this.id, tagID, tagType]);
 				let notifierData = {};
 				notifierData[this.id + '-' + tagID] = {
 					libraryID: this.libraryID,
-					tag: tag.tag
+					tag: tag.tag,
+					type: tagType
 				};
 
 				if (!env.options.skipNotifier) {
diff --git a/chrome/content/zotero/xpcom/data/tags.js b/chrome/content/zotero/xpcom/data/tags.js
index 974faa4a39..4fd19186f2 100644
--- a/chrome/content/zotero/xpcom/data/tags.js
+++ b/chrome/content/zotero/xpcom/data/tags.js
@@ -137,39 +137,63 @@ Zotero.Tags = new function() {
 	 * Get all tags in library
 	 *
 	 * @param {Number} libraryID
-	 * @param {Array}  [types]    Tag types to fetch
+	 * @param {Number[]} [types] - Tag types to fetch
 	 * @return {Promise<Array>}   A promise for an array containing tag objects in API JSON format
 	 *                            [{ { tag: "foo" }, { tag: "bar", type: 1 }]
 	 */
-	this.getAll = Zotero.Promise.coroutine(function* (libraryID, types) {
-		var sql = "SELECT DISTINCT name AS tag, type FROM tags "
-			+ "JOIN itemTags USING (tagID) JOIN items USING (itemID) WHERE libraryID=?";
-		var params = [libraryID];
-		if (types) {
-			sql += " AND type IN (" + types.join() + ")";
-		}
-		var rows = yield Zotero.DB.queryAsync(sql, params);
-		return rows.map((row) => this.cleanData(row));
-	});
+	this.getAll = async function (libraryID, types) {
+		return this.getAllWithin({ libraryID, types });
+	};
 	
 	
 	/**
 	 * Get all tags within the items of a temporary table of search results
 	 *
-	 * @param {String} tmpTable  Temporary table with items to use
-	 * @param {Array} [types]  Array of tag types to fetch
-	 * @return {Promise<Object>}  Promise for object with tag data in API JSON format, keyed by tagID
+	 * @param {Object}
+	 * @param {Object.Number} libraryID
+	 * @param {Object.String} tmpTable - Temporary table with items to use
+	 * @param {Object.Number[]} [types] - Array of tag types to fetch
+	 * @param {Object.Number[]} [tagIDs] - Array of tagIDs to limit the result to
+	 * @return {Promise<Array[]>} - Promise for an array of tag objects in API JSON format
 	 */
-	this.getAllWithinSearchResults = Zotero.Promise.coroutine(function* (tmpTable, types) {
-		var sql = "SELECT DISTINCT name AS tag, type FROM itemTags "
-			+ "JOIN tags USING (tagID) WHERE itemID IN "
-			+ "(SELECT itemID FROM " + tmpTable + ") ";
-		if (types) {
-			sql += "AND type IN (" + types.join() + ") ";
+	this.getAllWithin = async function ({ libraryID, tmpTable, types, tagIDs }) {
+		// mozStorage/Proxy are slow, so get in a single column
+		var sql = "SELECT DISTINCT tagID || ':' || type FROM itemTags "
+			+ "JOIN tags USING (tagID) ";
+		var params = [];
+		if (libraryID) {
+			sql += "JOIN items USING (itemID) WHERE libraryID = ? ";
+			params.push(libraryID);
 		}
-		var rows = yield Zotero.DB.queryAsync(sql);
-		return rows.map((row) => this.cleanData(row));
-	});
+		else {
+			sql += "WHERE 1 ";
+		}
+		if (tmpTable) {
+			if (libraryID) {
+				throw new Error("tmpTable and libraryID are mutually exclusive");
+			}
+			sql += "AND itemID IN (SELECT itemID FROM " + tmpTable + ") ";
+		}
+		if (types && types.length) {
+			sql += "AND type IN (" + new Array(types.length).fill('?').join(', ') + ") ";
+			params.push(...types);
+		}
+		if (tagIDs) {
+			sql += "AND tagID IN (" + new Array(tagIDs.length).fill('?').join(', ') + ") ";
+			params.push(...tagIDs);
+		}
+		// Not a perfect locale sort, but speeds up the sort in the tag selector later without any
+		// discernible performance cost
+		sql += "ORDER BY name COLLATE NOCASE";
+		var rows = await Zotero.DB.columnQueryAsync(sql, params);
+		return rows.map((row) => {
+			var [tagID, type] = row.split(':');
+			return this.cleanData({
+				tag: Zotero.Tags.getName(parseInt(tagID)),
+				type: type
+			});
+		});
+	};
 	
 	
 	/**
diff --git a/chrome/content/zotero/zoteroPane.js b/chrome/content/zotero/zoteroPane.js
index 6c9bb8d9b5..2687c6d8c0 100644
--- a/chrome/content/zotero/zoteroPane.js
+++ b/chrome/content/zotero/zoteroPane.js
@@ -105,7 +105,7 @@ var ZoteroPane = new function()
 			this.updateWindow();
 			this.updateToolbarPosition();
 		});
-		window.setTimeout(ZoteroPane_Local.updateToolbarPosition, 0);
+		window.setTimeout(this.updateToolbarPosition.bind(this), 0);
 		
 		Zotero.updateQuickSearchBox(document);
 		
@@ -1103,13 +1103,21 @@ var ZoteroPane = new function()
 			this.tagSelector = Zotero.TagSelector.init(
 				document.getElementById('zotero-tag-selector'),
 				{
-					onSelection: this.updateTagFilter.bind(this)
+					container: 'zotero-tag-selector-container',
+					onSelection: this.updateTagFilter.bind(this),
 				}
 			);
 		}
 	};
 	
 	
+	this.handleTagSelectorResize = Zotero.Utilities.debounce(function() {
+		if (this.tagSelectorShown()) {
+			this.tagSelector.handleResize();
+		}
+	}, 100);
+	
+	
 	/*
 	 * Sets the tag filter on the items view
 	 */
@@ -1120,7 +1128,7 @@ var ZoteroPane = new function()
 	});
 	
 	
-	this.toggleTagSelector = Zotero.Promise.coroutine(function* () {
+	this.toggleTagSelector = function () {
 		var container = document.getElementById('zotero-tag-selector-container');
 		var showing = container.getAttribute('collapsed') == 'true';
 		container.setAttribute('collapsed', !showing);
@@ -1129,14 +1137,15 @@ var ZoteroPane = new function()
 		// and focus filter textbox
 		if (showing) {
 			this.initTagSelector();
-			yield this.setTagScope();
 			ZoteroPane.tagSelector.focusTextbox();
+			this.setTagScope();
 		}
 		// If hiding, clear selection
 		else {
 			ZoteroPane.tagSelector.uninit();
+			ZoteroPane.tagSelector = null;
 		}
-	});
+	};
 	
 	
 	this.tagSelectorShown = function () {
@@ -1153,7 +1162,7 @@ var ZoteroPane = new function()
 	 *
 	 * Passed to the items tree to trigger on changes
 	 */
-	this.setTagScope = async function () {
+	this.setTagScope = function () {
 		var collectionTreeRow = self.getCollectionTreeRow();
 		if (self.tagSelectorShown()) {
 			if (collectionTreeRow.editable) {
@@ -1163,9 +1172,8 @@ var ZoteroPane = new function()
 				ZoteroPane_Local.tagSelector.setMode('view');
 			}
 			ZoteroPane_Local.tagSelector.onItemViewChanged({
-				collectionTreeRow,
 				libraryID: collectionTreeRow.ref.libraryID,
-				tagsInScope: await collectionTreeRow.getChildTags()
+				collectionTreeRow
 			});
 		}
 	};
@@ -4849,8 +4857,9 @@ var ZoteroPane = new function()
 		var itemToolbar = document.getElementById("zotero-item-toolbar");
 		var tagSelector = document.getElementById("zotero-tag-selector");
 		
-		collectionsToolbar.style.width = collectionsPane.boxObject.width + 'px';
-		tagSelector.style.maxWidth = collectionsPane.boxObject.width + 'px';
+		var collectionsPaneWidth = collectionsPane.boxObject.width + 'px';
+		collectionsToolbar.style.width = collectionsPaneWidth;
+		tagSelector.style.maxWidth = collectionsPaneWidth;
 		
 		if (stackedLayout || itemPane.collapsed) {
 		// The itemsToolbar and itemToolbar share the same space, and it seems best to use some flex attribute from right (because there might be other icons appearing or vanishing).
@@ -4876,6 +4885,8 @@ var ZoteroPane = new function()
 		// Allow item pane to shrink to available height in stacked mode, but don't expand to be too
 		// wide when there's no persisted width in non-stacked mode
 		itemPane.setAttribute("flex", stackedLayout ? 1 : 0);
+		
+		this.handleTagSelectorResize();
 	}
 	
 	/**
diff --git a/chrome/content/zotero/zoteroPane.xul b/chrome/content/zotero/zoteroPane.xul
index 590fa490d2..66809b8895 100644
--- a/chrome/content/zotero/zoteroPane.xul
+++ b/chrome/content/zotero/zoteroPane.xul
@@ -306,8 +306,12 @@
 							ondragover="return ZoteroPane_Local.collectionsView.onDragOver(event)"
 							ondrop="return ZoteroPane_Local.collectionsView.onDrop(event)"/>
 					</tree>
-					<splitter id="zotero-tags-splitter" collapse="after"
-							zotero-persist="state">
+					<splitter
+							id="zotero-tags-splitter"
+							collapse="after"
+							zotero-persist="state"
+							onmousemove="if (this.getAttribute('state') == 'dragging') { ZoteroPane.handleTagSelectorResize(); }"
+					>
 						<grippy oncommand="ZoteroPane_Local.toggleTagSelector()"/>
 					</splitter>
 					<!-- 'collapsed' is no longer necessary here due to the persisted 'state' on
diff --git a/chrome/skin/default/zotero/bindings/tagsbox.css b/chrome/skin/default/zotero/bindings/tagsbox.css
index d5c0ab06a9..3ed688e30c 100644
--- a/chrome/skin/default/zotero/bindings/tagsbox.css
+++ b/chrome/skin/default/zotero/bindings/tagsbox.css
@@ -1,3 +1,7 @@
 textbox {
 	margin: 0;
 }
+
+row > label {
+	white-space: pre;
+}
diff --git a/package-lock.json b/package-lock.json
index a64979c555..28b49157c9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -647,6 +647,23 @@
         "@babel/plugin-transform-react-jsx-source": "^7.0.0"
       }
     },
+    "@babel/runtime": {
+      "version": "7.4.2",
+      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.4.2.tgz",
+      "integrity": "sha512-7Bl2rALb7HpvXFL7TETNzKSAeBVCPHELzc0C//9FCxN8nsiueWSJBqaF+2oIJScyILStASR/Cx5WMkXGYTiJFA==",
+      "dev": true,
+      "requires": {
+        "regenerator-runtime": "^0.13.2"
+      },
+      "dependencies": {
+        "regenerator-runtime": {
+          "version": "0.13.2",
+          "resolved": "https://registry.npmjs.org/regenerator-runtime/-/regenerator-runtime-0.13.2.tgz",
+          "integrity": "sha512-S/TQAZJO+D3m9xeN1WTI8dLKBBiRgXBlTJvbWjCThHWZj9EvHK70Ff50/tYj2J/fvBY6JtFVwRuazHN2E7M9BA==",
+          "dev": true
+        }
+      }
+    },
     "@babel/template": {
       "version": "7.2.2",
       "resolved": "https://registry.npmjs.org/@babel/template/-/template-7.2.2.tgz",
@@ -2139,6 +2156,15 @@
         "esutils": "^2.0.2"
       }
     },
+    "dom-helpers": {
+      "version": "3.4.0",
+      "resolved": "https://registry.npmjs.org/dom-helpers/-/dom-helpers-3.4.0.tgz",
+      "integrity": "sha512-LnuPJ+dwqKDIyotW1VzmOZ5TONUN7CwkCR5hrgawTUbkBGYdeoNLZo6nNfGkCrjtE1nXXaj7iMMpDa8/d9WoIA==",
+      "dev": true,
+      "requires": {
+        "@babel/runtime": "^7.1.2"
+      }
+    },
     "domain-browser": {
       "version": "1.1.7",
       "resolved": "https://registry.npmjs.org/domain-browser/-/domain-browser-1.1.7.tgz",
@@ -5448,6 +5474,26 @@
         "invariant": "^2.1.1"
       }
     },
+    "react-lifecycles-compat": {
+      "version": "3.0.4",
+      "resolved": "https://registry.npmjs.org/react-lifecycles-compat/-/react-lifecycles-compat-3.0.4.tgz",
+      "integrity": "sha512-fBASbA6LnOU9dOU2eW7aQ8xmYBSXUIWr+UmF9b1efZBazGNO+rcXT/icdKnYm2pTwcRylVUYwW7H1PHfLekVzA==",
+      "dev": true
+    },
+    "react-virtualized": {
+      "version": "9.21.0",
+      "resolved": "https://registry.npmjs.org/react-virtualized/-/react-virtualized-9.21.0.tgz",
+      "integrity": "sha512-duKD2HvO33mqld4EtQKm9H9H0p+xce1c++2D5xn59Ma7P8VT7CprfAe5hwjd1OGkyhqzOZiTMlTal7LxjH5yBQ==",
+      "dev": true,
+      "requires": {
+        "babel-runtime": "^6.26.0",
+        "classnames": "^2.2.3",
+        "dom-helpers": "^2.4.0 || ^3.0.0",
+        "loose-envify": "^1.3.0",
+        "prop-types": "^15.6.0",
+        "react-lifecycles-compat": "^3.0.4"
+      }
+    },
     "read-only-stream": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/read-only-stream/-/read-only-stream-2.0.0.tgz",
diff --git a/package.json b/package.json
index 0860a1a5cb..cd33b252a6 100644
--- a/package.json
+++ b/package.json
@@ -44,6 +44,7 @@
     "mocha": "^3.5.3",
     "multimatch": "^2.1.0",
     "node-sass": "^4.11.0",
+    "react-virtualized": "^9.21.0",
     "sinon": "^4.5.0",
     "universalify": "^0.1.1"
   }
diff --git a/resource/react-virtualized.js b/resource/react-virtualized.js
new file mode 120000
index 0000000000..f2c73afb9e
--- /dev/null
+++ b/resource/react-virtualized.js
@@ -0,0 +1 @@
+../node_modules/react-virtualized/dist/umd/react-virtualized.js
\ No newline at end of file
diff --git a/scripts/babel-worker.js b/scripts/babel-worker.js
index 2cd10505a8..ed5a7fb3f4 100644
--- a/scripts/babel-worker.js
+++ b/scripts/babel-worker.js
@@ -29,16 +29,24 @@ async function babelWorker(ev) {
 
 	try {
 		let contents = await fs.readFile(sourcefile, 'utf8');
+		// Patch react
 		if (sourcefile === 'resource/react.js') {
-			// patch react
 			transformed = contents.replace('instanceof Error', '.constructor.name == "Error"')
-		} else if (sourcefile === 'resource/react-dom.js') {
-			// and react-dom
+		}
+		// Patch react-dom
+		else if (sourcefile === 'resource/react-dom.js') {
 			transformed = contents.replace(/ ownerDocument\.createElement\((.*?)\)/gi, 'ownerDocument.createElementNS(HTML_NAMESPACE, $1)')
 				.replace('element instanceof win.HTMLIFrameElement',
 					'typeof element != "undefined" && element.tagName.toLowerCase() == "iframe"')
 				.replace("isInputEventSupported = false", 'isInputEventSupported = true');
-		} else if ('ignore' in options && options.ignore.some(ignoreGlob => multimatch(sourcefile, ignoreGlob).length)) {
+		}
+		// Patch react-virtualized
+		else if (sourcefile === 'resource/react-virtualized.js') {
+			transformed = contents.replace('scrollDiv = document.createElement("div")', 'scrollDiv = document.createElementNS("http://www.w3.org/1999/xhtml", "div")')
+				.replace('document.body.appendChild(scrollDiv)', 'document.documentElement.appendChild(scrollDiv)')
+				.replace('document.body.removeChild(scrollDiv)', 'document.documentElement.removeChild(scrollDiv)');
+		}
+		else if ('ignore' in options && options.ignore.some(ignoreGlob => multimatch(sourcefile, ignoreGlob).length)) {
 			transformed = contents;
 			isSkipped = true;
 		} else {
diff --git a/scripts/config.js b/scripts/config.js
index 31809baa31..817a31a861 100644
--- a/scripts/config.js
+++ b/scripts/config.js
@@ -31,6 +31,7 @@ const symlinkFiles = [
 	'resource/**/*',
 	'!resource/react.js',
 	'!resource/react-dom.js',
+	'!resource/react-virtualized.js',
 	'update.rdf'
 ];
 
@@ -64,6 +65,7 @@ const jsFiles = [
 	// Special handling for React -- see note above
 	'resource/react.js',
 	'resource/react-dom.js',
+	'resource/react-virtualized.js',
 ];
 
 const scssFiles = [
diff --git a/scss/components/_tag-selector.scss b/scss/components/_tag-selector.scss
index 9009cf3961..3978815fa5 100644
--- a/scss/components/_tag-selector.scss
+++ b/scss/components/_tag-selector.scss
@@ -1,6 +1,19 @@
 //
 // Tag selector
 // --------------------------------------------------
+#zotero-tag-selector-container {
+	display: flex;
+}
+
+#zotero-tag-selector-container[collapsed=true] {
+	visibility: collapse;
+}
+
+#zotero-tag-selector {
+	min-height: 100px;
+	width: 100%;
+	display: flex;
+}
 
 .tag-selector {
 	display: flex;
@@ -9,14 +22,19 @@
 	overflow: hidden;
 }
 
-.tag-selector-container {
+.tag-selector-list-container {
 	flex: 1 1 auto;
 	justify-content: space-between;
-	overflow: auto;
+	display: flex;
+	overflow: hidden;
 	height: 100px;
 	background-color: $tag-selector-bg;
 }
 
+.tag-selector-list-container > div {
+	flex: 1 1 auto;
+}
+
 .tag-selector-message {
 	display: flex;
 	align-items: center;
@@ -32,7 +50,7 @@
 }
 
 .tag-selector-filter-container {
-	height: auto;
+	height: 30px;
 	flex: 0 0 1em;
 	display: flex;
 	flex-direction: row;
@@ -53,13 +71,10 @@
 
 .tag-selector-item {
 	cursor: pointer;
-	display: inline-block;
-	margin: .15em .05em .15em .3em;
-	padding: 0 .25em 0 .25em;
-	max-width: 250px;
 	overflow: hidden;
 	text-overflow: ellipsis;
-	white-space: nowrap;
+	white-space: pre;
+	padding: 1px 4px 3px;
 
 	&.colored {
 		font-weight: bold;
@@ -75,17 +90,3 @@
 		background: $shade-6;
 	}
 }
-
-#zotero-tag-selector-container {
-	display: flex;
-}
-
-#zotero-tag-selector-container[collapsed=true] {
-	visibility: collapse;
-}
-
-#zotero-tag-selector {
-	min-height: 100px;
-	width: 100%;
-	display: flex;
-}
diff --git a/test/tests/tagSelectorTest.js b/test/tests/tagSelectorTest.js
index 6c52da977f..d78052d01c 100644
--- a/test/tests/tagSelectorTest.js
+++ b/test/tests/tagSelectorTest.js
@@ -1,7 +1,7 @@
 "use strict";
 
 describe("Tag Selector", function () {
-	var win, doc, collectionsView, tagSelectorElem, tagSelector;
+	var libraryID, win, doc, collectionsView, tagSelectorElem, tagSelector;
 	
 	var clearTagColors = Zotero.Promise.coroutine(function* (libraryID) {
 		var tagColors = Zotero.Tags.getColors(libraryID);
@@ -11,17 +11,25 @@ describe("Tag Selector", function () {
 	});
 	
 	function getColoredTags() {
-		var elems = Array.from(tagSelectorElem.querySelectorAll('.tag-selector-item.colored'));
-		return elems.map(elem => elem.textContent);
+		return [...getColoredTagElements()].map(elem => elem.textContent);
+	}
+	
+	function getColoredTagElements() {
+		return tagSelectorElem.querySelectorAll('.tag-selector-item.colored');
 	}
 	
 	function getRegularTags() {
-		var elems = Array.from(tagSelectorElem.querySelectorAll('.tag-selector-item:not(.colored)'));
-		return elems.map(elem => elem.textContent);
+		return [...getRegularTagElements()].map(elem => elem.textContent);
+	}
+	
+	function getRegularTagElements() {
+		return tagSelectorElem.querySelectorAll('.tag-selector-item:not(.colored)');
 	}
 	
 	
 	before(function* () {
+		libraryID = Zotero.Libraries.userLibraryID;
+		
 		win = yield loadZoteroPane();
 		doc = win.document;
 		collectionsView = win.ZoteroPane.collectionsView;
@@ -32,15 +40,18 @@ describe("Tag Selector", function () {
 		yield Zotero.Promise.delay(100);
 	});
 	
-	beforeEach(function* () {
-		var libraryID = Zotero.Libraries.userLibraryID;
-		yield clearTagColors(libraryID);
+	beforeEach(async function () {
+		await selectLibrary(win);
+		await clearTagColors(libraryID);
 		// Default "Display All Tags in This Library" off
 		tagSelector.displayAllTags = false;
 		tagSelector.selectedTags = new Set();
 		tagSelector.handleSearch('');
-		tagSelector.onItemViewChanged({libraryID});
-		yield waitForTagSelector(win);
+		tagSelector.onItemViewChanged({
+			collectionTreeRow: win.ZoteroPane.getCollectionTreeRow(),
+			libraryID
+		});
+		await waitForTagSelector(win);
 	});
 	
 	after(function () {
@@ -48,7 +59,6 @@ describe("Tag Selector", function () {
 	});
 	
 	it("should sort colored tags by assigned number key", async function () {
-		var libraryID = Zotero.Libraries.userLibraryID;
 		var collection = await createDataObject('collection');
 		
 		await Zotero.Tags.setColor(libraryID, "B", '#AAAAAA', 1);
@@ -156,25 +166,17 @@ describe("Tag Selector", function () {
 		it("should show all tags in library when true", function* () {
 			tagSelector.displayAllTags = true;
 			
+			var tag1 = 'A ' + Zotero.Utilities.randomString();
+			var tag2 = 'B ' + Zotero.Utilities.randomString();
+			var tag3 = 'C ' + Zotero.Utilities.randomString();
+			
 			var collection = yield createDataObject('collection');
 			var item1 = createUnsavedDataObject('item');
-			item1.setTags([
-				{
-					tag: "A"
-				}
-			]);
+			item1.setTags([tag1]);
 			var item2 = createUnsavedDataObject('item', { collections: [collection.id] });
-			item2.setTags([
-				{
-					tag: "B"
-				}
-			]);
+			item2.setTags([tag2]);
 			var item3 = createUnsavedDataObject('item', { collections: [collection.id] });
-			item3.setTags([
-				{
-					tag: "C"
-				}
-			]);
+			item3.setTags([tag3]);
 			var promise = waitForTagSelector(win);
 			yield Zotero.DB.executeTransaction(function* () {
 				yield item1.save();
@@ -184,7 +186,15 @@ describe("Tag Selector", function () {
 			yield promise;
 			
 			var tags = getRegularTags();
-			assert.sameMembers(tags, ['A', 'B', 'C']);
+			assert.includeMembers(tags, [tag1, tag2, tag3]);
+			assert.isBelow(tags.indexOf(tag1), tags.indexOf(tag2));
+			assert.isBelow(tags.indexOf(tag2), tags.indexOf(tag3));
+			
+			var elems = getRegularTagElements();
+			// Tag not associated with any items in this collection should be disabled
+			assert.isTrue(elems[tags.indexOf(tag1)].classList.contains('disabled'));
+			assert.isFalse(elems[tags.indexOf(tag2)].classList.contains('disabled'));
+			assert.isFalse(elems[tags.indexOf(tag3)].classList.contains('disabled'));
 		});
 	});
 	
@@ -199,16 +209,18 @@ describe("Tag Selector", function () {
 				await promise;
 			}
 			
-			// Add item with tag to library root
-			var tagA = Zotero.Utilities.randomString();
-			var tagB = Zotero.Utilities.randomString();
+			// Add item with tags to library root
+			var tag1 = 'A ' + Zotero.Utilities.randomString();
+			var tag2 = 'M ' + Zotero.Utilities.randomString();
+			var tag3 = 'Z ' + Zotero.Utilities.randomString();
+			
 			var item = createUnsavedDataObject('item');
 			item.setTags([
 				{
-					tag: tagA
+					tag: tag3
 				},
 				{
-					tag: tagB,
+					tag: tag1,
 					type: 1
 				}
 			]);
@@ -216,7 +228,20 @@ describe("Tag Selector", function () {
 			await item.saveTx();
 			await promise;
 			
-			assert.includeMembers(getRegularTags(), [tagA, tagB]);
+			var tags = getRegularTags();
+			assert.includeMembers(tags, [tag1, tag3]);
+			assert.isBelow(tags.indexOf(tag1), tags.indexOf(tag3));
+			
+			// Add another tag to the item, sorted between the two other tags
+			promise = waitForTagSelector(win);
+			item.addTag(tag2);
+			await item.saveTx();
+			await promise;
+			
+			var tags = getRegularTags();
+			assert.includeMembers(tags, [tag1, tag2, tag3]);
+			assert.isBelow(tags.indexOf(tag1), tags.indexOf(tag2));
+			assert.isBelow(tags.indexOf(tag2), tags.indexOf(tag3));
 		});
 		
 		it("should add a tag when an item is added in a collection", function* () {
@@ -244,7 +269,112 @@ describe("Tag Selector", function () {
 			
 			// Tag selector should show the new item's tag
 			assert.equal(getRegularTags().length, 1);
-		})
+		});
+		
+		it("should update colored tag disabled state when items are added to and removed from collection", async function () {
+			var tag1 = 'A ' + Zotero.Utilities.randomString();
+			var tag2 = 'B ' + Zotero.Utilities.randomString();
+			var tag3 = 'C ' + Zotero.Utilities.randomString();
+			
+			// Add collection
+			var promise = waitForTagSelector(win);
+			var collection = await createDataObject('collection');
+			await promise;
+			
+			var elems = getColoredTagElements();
+			assert.lengthOf(elems, 0);
+			
+			await Zotero.Tags.setColor(libraryID, tag1, '#AAAAAA', 1);
+			await Zotero.Tags.setColor(libraryID, tag2, '#BBBBBB', 2);
+			await Zotero.Tags.setColor(libraryID, tag3, '#CCCCCC', 3);
+			
+			// Colored tags should appear initially as disabled
+			elems = getColoredTagElements();
+			assert.lengthOf(elems, 3);
+			assert.isTrue(elems[0].classList.contains('disabled'));
+			assert.isTrue(elems[1].classList.contains('disabled'));
+			assert.isTrue(elems[2].classList.contains('disabled'));
+			
+			// Add items with tags to collection
+			promise = waitForTagSelector(win)
+			var item1;
+			var item2;
+			await Zotero.DB.executeTransaction(async function () {
+				item1 = createUnsavedDataObject('item', { collections: [collection.id], tags: [tag1, tag2] });
+				item2 = createUnsavedDataObject('item', { collections: [collection.id], tags: [tag2] });
+				await item1.save();
+				await item2.save();
+			});
+			await promise;
+			
+			elems = getColoredTagElements();
+			assert.lengthOf(elems, 3);
+			// Assigned tags should be enabled
+			assert.isFalse(elems[0].classList.contains('disabled'));
+			assert.isFalse(elems[1].classList.contains('disabled'));
+			// Unassigned tag should still be disabled
+			assert.isTrue(elems[2].classList.contains('disabled'));
+			
+			// Remove item from collection
+			promise = waitForTagSelector(win)
+			item1.removeFromCollection(collection.id);
+			await item1.saveTx();
+			await promise;
+			
+			// A and C should be disabled
+			elems = getColoredTagElements();
+			assert.lengthOf(elems, 3);
+			assert.isTrue(elems[0].classList.contains('disabled'));
+			assert.isFalse(elems[1].classList.contains('disabled'));
+			assert.isTrue(elems[2].classList.contains('disabled'));
+		});
+		
+		it("should update colored tag disabled state when tags are added to and removed from items", async function () {
+			var tag1 = 'A ' + Zotero.Utilities.randomString();
+			var tag2 = 'B ' + Zotero.Utilities.randomString();
+			var tag3 = 'C ' + Zotero.Utilities.randomString();
+			
+			var elems = getColoredTagElements();
+			assert.lengthOf(elems, 0);
+			
+			await Zotero.Tags.setColor(libraryID, tag1, '#AAAAAA', 1);
+			await Zotero.Tags.setColor(libraryID, tag2, '#BBBBBB', 2);
+			await Zotero.Tags.setColor(libraryID, tag3, '#CCCCCC', 3);
+			
+			// Add items to collection
+			var item1 = await createDataObject('item');
+			var item2 = await createDataObject('item');
+			
+			var promise = waitForTagSelector(win)
+			await Zotero.DB.executeTransaction(async function () {
+				item1.setTags([tag1, tag2]);
+				item2.setTags([tag1]);
+				await item1.save();
+				await item2.save();
+			});
+			await promise;
+			
+			elems = getColoredTagElements();
+			assert.lengthOf(elems, 3);
+			// Assigned tags should be enabled
+			assert.isFalse(elems[0].classList.contains('disabled'));
+			assert.isFalse(elems[1].classList.contains('disabled'));
+			// Unassigned tag should still be disabled
+			assert.isTrue(elems[2].classList.contains('disabled'));
+			
+			// Remove tags from one item
+			promise = waitForTagSelector(win)
+			item1.setTags([]);
+			await item1.saveTx();
+			await promise;
+			
+			// B and C should be disabled
+			elems = getColoredTagElements();
+			assert.lengthOf(elems, 3);
+			assert.isFalse(elems[0].classList.contains('disabled'));
+			assert.isTrue(elems[1].classList.contains('disabled'));
+			assert.isTrue(elems[2].classList.contains('disabled'));
+		});
 		
 		it("should add a tag when an item is added to a collection", function* () {
 			var promise, tagSelector;
@@ -264,9 +394,7 @@ describe("Tag Selector", function () {
 					tag: 'C'
 				}
 			]);
-			promise = waitForTagSelector(win)
 			yield item.saveTx();
-			yield promise;
 			
 			// Tag selector should still be empty in collection
 			assert.equal(getRegularTags().length, 0);
@@ -281,8 +409,6 @@ describe("Tag Selector", function () {
 		})
 		
 		it("should show a colored tag at the top of the list even when linked to no items", function* () {
-			var libraryID = Zotero.Libraries.userLibraryID;
-			
 			var tagElems = tagSelectorElem.querySelectorAll('.tag-selector-item');
 			var count = tagElems.length;
 
@@ -295,8 +421,6 @@ describe("Tag Selector", function () {
 		});
 		
 		it("shouldn't re-insert a new tag that matches an existing color", function* () {
-			var libraryID = Zotero.Libraries.userLibraryID;
-			
 			// Add A and B as colored tags without any items
 			yield Zotero.Tags.setColor(libraryID, "A", '#CC9933', 1);
 			yield Zotero.Tags.setColor(libraryID, "B", '#990000', 2);
@@ -383,6 +507,43 @@ describe("Tag Selector", function () {
 			assert.equal(getRegularTags().length, 0);
 		})
 		
+		it("shouldn't remove a tag when a tag is removed from an item in a collection in displayAllTags mode", async function () {
+			tagSelector.displayAllTags = true;
+			
+			var tag = Zotero.Utilities.randomString();
+			
+			// Add item with tag not in collection
+			var promise = waitForTagSelector(win);
+			var item1 = await createDataObject('item', { tags: [tag] });
+			await promise;
+			
+			promise = waitForTagSelector(win);
+			var collection = await createDataObject('collection');
+			await promise;
+			
+			// Add item with tag to collection
+			promise = waitForTagSelector(win);
+			var item2 = await createDataObject('item', { collections: [collection.id], tags: [tag] });
+			await promise;
+			
+			// Tag selector should show the new item's tag
+			var tags = getRegularTags();
+			assert.include(tags, tag);
+			var elems = getRegularTagElements();
+			assert.isFalse(elems[tags.indexOf(tag)].classList.contains('disabled'));
+			
+			item2.removeTag(tag);
+			promise = waitForTagSelector(win);
+			await item2.saveTx();
+			await promise;
+			
+			// Tag selector should still show the removed item's tag
+			tags = getRegularTags();
+			assert.include(tags, tag);
+			elems = getRegularTagElements();
+			assert.isTrue(elems[tags.indexOf(tag)].classList.contains('disabled'));
+		});
+		
 		it("should remove a tag when a tag is deleted for a library", function* () {
 			yield selectLibrary(win);
 			
@@ -411,7 +572,6 @@ describe("Tag Selector", function () {
 		});
 		
 		it("should deselect a tag when removed from the last item in this view", async function () {
-			var libraryID = Zotero.Libraries.userLibraryID;
 			await selectLibrary(win);
 			
 			var tag1 = Zotero.Utilities.randomString();
@@ -447,7 +607,6 @@ describe("Tag Selector", function () {
 		});
 		
 		it("should deselect a tag when deleted from a library", async function () {
-			var libraryID = Zotero.Libraries.userLibraryID;
 			await selectLibrary(win);
 			
 			var promise = waitForTagSelector(win, 2);
@@ -517,7 +676,6 @@ describe("Tag Selector", function () {
 			var oldTag = Zotero.Utilities.randomString();
 			var newTag = Zotero.Utilities.randomString();
 			
-			var libraryID = Zotero.Libraries.userLibraryID;
 			var promise = waitForTagSelector(win);
 			yield Zotero.Tags.setColor(libraryID, oldTag, "#F3F3F3");
 			yield promise;