diff --git a/gitnexus/src/core/ingestion/languages/r/scope-resolver.ts b/gitnexus/src/core/ingestion/languages/r/scope-resolver.ts
index 48c389e5d..0d32be7e6 100644
--- a/gitnexus/src/core/ingestion/languages/r/scope-resolver.ts
+++ b/gitnexus/src/core/ingestion/languages/r/scope-resolver.ts
@@ -34,6 +34,7 @@ import type { GraphNodeLookup } from '../../scope-resolution/graph-bridge/node-l
 import type { KnowledgeGraph } from '../../../graph/types.js';
 import { generateId } from '../../../../lib/utils.js';
 import { loadRPackageConfig } from './package-config.js';
+import { perFileSet } from '../../import-resolvers/per-file-set.js';
 import { resolveRImportTarget } from '../../import-resolvers/r.js';
 import {
   isRGlobalNameFallbackPlausible,
@@ -103,6 +104,23 @@ function emitRVirtualHeritageEdges(
   }
 }
 
+/**
+ * `moduleScope` → its `ParsedFile`, built once per pass and keyed on the identity of the pass's
+ * `parsedFiles` array, which finalize passes unchanged to every `expandsWildcardTo` call. The
+ * lookup used to be `parsedFiles.find`, one scan of all files per `library()` edge: 450,000 edges
+ * over 3,000 files took 5.9 s. As in the C, C++ and Python providers, the first file wins on a
+ * repeated scope, as `find` did.
+ */
+const parsedFileByModuleScope = perFileSet(
+  (parsedFiles: readonly ParsedFile[]): Map<ScopeId, ParsedFile> => {
+    const index = new Map<ScopeId, ParsedFile>();
+    for (const parsed of parsedFiles) {
+      if (!index.has(parsed.moduleScope)) index.set(parsed.moduleScope, parsed);
+    }
+    return index;
+  },
+);
+
 /**
  * Enumerate all top-level names exported from a target module scope's file
  * (module-scope function and class bindings; functions nested in another function are not).
@@ -126,7 +144,7 @@ export function expandRWildcardNames(
   targetModuleScope: ScopeId,
   parsedFiles: readonly ParsedFile[],
 ): readonly string[] {
-  const target = parsedFiles.find((p) => p.moduleScope === targetModuleScope);
+  const target = parsedFileByModuleScope(parsedFiles).get(targetModuleScope);
   if (target === undefined) return [];
   const { names: topLevel, dottedTails } = rFileTopLevel(target);
   const seen = new Set<string>();
diff --git a/gitnexus/test/unit/scope-resolution/r/r-dotted-s3-hooks.test.ts b/gitnexus/test/unit/scope-resolution/r/r-dotted-s3-hooks.test.ts
index 3df1da79d..67938d658 100644
--- a/gitnexus/test/unit/scope-resolution/r/r-dotted-s3-hooks.test.ts
+++ b/gitnexus/test/unit/scope-resolution/r/r-dotted-s3-hooks.test.ts
@@ -13,6 +13,7 @@ import {
   rIsCallableVisibleFromCaller,
   rScopeResolver,
 } from '../../../../src/core/ingestion/languages/r/scope-resolver.js';
+import { countedParsedFiles } from '../../../helpers/counting-file-set.js';
 
 function parse(src: string, filePath: string): ParsedFile {
   const parsed = extractParsedFile(rProvider, src, filePath);
@@ -146,3 +147,21 @@ describe('expandRWildcardNames', () => {
     expect(expandRWildcardNames('scope:missing' as never, [a])).toEqual([]);
   });
 });
+
+describe('expandRWildcardNames: the module-scope lookup is built once per pass', () => {
+  it('reads each parsed file once however many wildcard edges ask', () => {
+    // `parsedFiles.find` per edge read the files up to the match every time. Counted element
+    // reads, not wall time: the figure depends on the file count and the number of passes only.
+    const paths = Array.from({ length: 200 }, (_, i) => `pkg/R/f${i}.R`);
+    const { parsedFiles, reads } = countedParsedFiles(paths);
+    for (let edge = 0; edge < 1_000; edge++) {
+      expandRWildcardNames(`module:${paths[(edge * 7) % paths.length]}`, parsedFiles);
+    }
+    expect(reads()).toBe(paths.length);
+  });
+
+  it('answers a scope no file owns with nothing', () => {
+    const { parsedFiles } = countedParsedFiles(['pkg/R/a.R']);
+    expect(expandRWildcardNames('module:absent' as never, parsedFiles)).toEqual([]);
+  });
+});