diff --git a/devtools/shared/DevToolsUtils.js b/devtools/shared/DevToolsUtils.js
index d80d87ece9f..6a625838193 100644
--- a/devtools/shared/DevToolsUtils.js
+++ b/devtools/shared/DevToolsUtils.js
@@ -189,10 +189,17 @@ exports.executeSoon = function executeSoon(aFn) {
   if (isWorker) {
     setImmediate(aFn);
   } else {
-    let stack = components.stack;
-    let executor = () => {
-      Cu.callFunctionWithAsyncStack(aFn, stack, "DevToolsUtils.executeSoon");
-    };
+    let executor;
+    // Only enable async stack reporting when DEBUG_JS_MODULES is set
+    // (customized local builds) to avoid a performance penalty.
+    if (AppConstants.DEBUG_JS_MODULES || exports.testing) {
+      let stack = components.stack;
+      executor = () => {
+        Cu.callFunctionWithAsyncStack(aFn, stack, "DevToolsUtils.executeSoon");
+      };
+    } else {
+      executor = aFn;
+    }
     Services.tm.mainThread.dispatch({
       run: exports.makeInfallible(executor)
     }, Ci.nsIThread.DISPATCH_NORMAL);
diff --git a/devtools/shared/tests/unit/head_devtools.js b/devtools/shared/tests/unit/head_devtools.js
index 8a93c7174fd..5b66328eec0 100644
--- a/devtools/shared/tests/unit/head_devtools.js
+++ b/devtools/shared/tests/unit/head_devtools.js
@@ -7,6 +7,11 @@ var Cr = Components.results;
 var {require} = Cu.import("resource://devtools/shared/Loader.jsm");
 const DevToolsUtils = require("devtools/shared/DevToolsUtils");
 
+DevToolsUtils.testing = true;
+do_register_cleanup(() => {
+  DevToolsUtils.testing = false;
+});
+
 // Register a console listener, so console messages don't just disappear
 // into the ether.