diff --git a/api.go b/api.go
index 5123f8afb..a5c6f4202 100644
--- a/api.go
+++ b/api.go
@@ -59,6 +59,8 @@ type API struct {
 	importWorkerPoolSize int
 	importWork           chan importJob
 
+	usageCache map[string]NodeUsage
+
 	Serializer Serializer
 }
 
@@ -934,9 +936,11 @@ func (api *API) Usage(ctx context.Context, remote bool) (map[string]NodeUsage, e
 	span, _ := tracing.StartSpanFromContext(ctx, "API.Usage")
 	defer span.Finish()
 
-	nodeUsages := make(map[string]NodeUsage)
+	if api.usageCache == nil {
+		api.usageCache = make(map[string]NodeUsage)
+	}
 
-	indexDetails, nodeMetadataBytes, err := api.holder.Txf().IndexUsageDetails()
+	indexDetails, nodeMetadataBytes, err := api.holder.Txf().IndexUsageDetails(api.usageCache[api.server.nodeID].Disk.IndexUsage)
 	if err != nil {
 		return nil, errors.Wrap(err, "getting node usage")
 	}
diff --git a/txfactory.go b/txfactory.go
index 8a2b987cb..f4373658b 100644
--- a/txfactory.go
+++ b/txfactory.go
@@ -572,7 +572,7 @@ func (f *TxFactory) DumpAll() {
 
 // IndexUsageDetails computes the sum of filesizes used by the node, broken down
 // by index, field, fragments and keys.
-func (f *TxFactory) IndexUsageDetails() (map[string]IndexUsage, uint64, error) {
+func (f *TxFactory) IndexUsageDetails(cache *map[string]IndexUsage) (map[string]IndexUsage, uint64, error) {
 	indexUsage := make(map[string]IndexUsage)
 	holderPath, err := expandDirName(f.holder.path)
 	if err != nil {