diff --git a/tensorboard/defs/defs.bzl b/tensorboard/defs/defs.bzl
index 75bd2f1a15f..f8c68e6f2ee 100644
--- a/tensorboard/defs/defs.bzl
+++ b/tensorboard/defs/defs.bzl
@@ -77,6 +77,10 @@ def tf_js_binary(
         terser_minified(
             name = internal_result_name,
             src = internal_rollup_name,
+            # Notes about the terser config:
+            # compress.passes - this is set to '1' to workaround issue with
+            #   terser and threejs. In practice it (surprisingly) generates
+            #   smaller results than when it was previously set to '3'.
             config_file = "//tensorboard/defs:terser_config.json",
             visibility = ["//visibility:private"],
             sourcemap = False,
diff --git a/tensorboard/defs/terser_config.json b/tensorboard/defs/terser_config.json
index 78914c24e37..7c2d5c7bfbb 100644
--- a/tensorboard/defs/terser_config.json
+++ b/tensorboard/defs/terser_config.json
@@ -4,7 +4,7 @@
   },
   "compress": {
     "keep_fnames": true,
-    "passes": 3,
+    "passes": 1,
     "pure_getters": true,
     "reduce_funcs": true,
     "reduce_vars": true,