link to relevant jsperf

platform/firefox/vapi-background.js

@@ -804,6 +804,8 @@ vAPI.messaging.broadcast = function(message) {
 // "the dreaded 'uniformly slow code' case where every function takes 1% 
 //  of CPU and you have to make one hundred separate performance optimizations 
 //  to improve performance at all"
+//
+// http://jsperf.com/closure-no-closure/2
 
 var CallbackWrapper = function(messageManager, channelName, listenerId, requestId) {
     this.callback = this.proxy.bind(this); // bind once