diff --git a/gopls/internal/lsp/cache/analysis.go b/gopls/internal/lsp/cache/analysis.go
index 7efb4ed..c5cda14 100644
--- a/gopls/internal/lsp/cache/analysis.go
+++ b/gopls/internal/lsp/cache/analysis.go
@@ -643,6 +643,9 @@
 			return nil, err
 		}
 		go func() {
+			cacheLimit <- unit{}            // acquire token
+			defer func() { <-cacheLimit }() // release token
+
 			data := analyzeSummaryCodec.Encode(summary)
 			if false {
 				log.Printf("Set key=%d value=%d id=%s\n", len(key), len(data), an.m.ID)
@@ -656,6 +659,10 @@
 	return summary, nil
 }
 
+// cacheLimit reduces parallelism of cache updates.
+// We allow more than typical GOMAXPROCS as it's a mix of CPU and I/O.
+var cacheLimit = make(chan unit, 32)
+
 // analysisCacheKey returns a cache key that is a cryptographic digest
 // of the all the values that might affect type checking and analysis:
 // the analyzer names, package metadata, names and contents of
@@ -747,6 +754,7 @@
 	parsed := make([]*source.ParsedGoFile, len(an.files))
 	{
 		var group errgroup.Group
+		group.SetLimit(4) // not too much: run itself is already called in parallel
 		for i, fh := range an.files {
 			i, fh := i, fh
 			group.Go(func() error {