From 8377e81827a840b9eb64f119de4bcbaba0ceb3be Mon Sep 17 00:00:00 2001
From: James deBoer <james@huronbox.com>
Date: Sun, 20 Apr 2014 08:24:01 -0700
Subject: [PATCH] perf(scope): 10x. Share the child scope class.

This change causes Scope.$destory to run 10x faster. I suspect
Scope.$new is significantly faster as well, but I didn't measure it.
---
 src/ng/rootScope.js | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/ng/rootScope.js b/src/ng/rootScope.js
index 274b36e8..0936ef6a 100644
--- a/src/ng/rootScope.js
+++ b/src/ng/rootScope.js
@@ -181,18 +181,23 @@ function $RootScopeProvider(){
           child.$$asyncQueue = this.$$asyncQueue;
           child.$$postDigestQueue = this.$$postDigestQueue;
         } else {
-          ChildScope = function() {}; // should be anonymous; This is so that when the minifier munges
-            // the name it does not become random set of chars. This will then show up as class
-            // name in the web inspector.
-          ChildScope.prototype = this;
-          child = new ChildScope();
-          child.$id = nextUid();
+          // Only create a child scope class if somebody asks for one,
+          // but cache it to allow the VM to optimize lookups.
+          if (!this.$$childScopeClass) {
+            this.$$childScopeClass = function() {
+              this.$$watchers = this.$$nextSibling =
+                  this.$$childHead = this.$$childTail = null;
+              this.$$listeners = {};
+              this.$$listenerCount = {};
+              this.$id = nextUid();
+              this.$$childScopeClass = null;
+            };
+            this.$$childScopeClass.prototype = this;
+          }
+          child = new this.$$childScopeClass();
         }
         child['this'] = child;
-        child.$$listeners = {};
-        child.$$listenerCount = {};
         child.$parent = this;
-        child.$$watchers = child.$$nextSibling = child.$$childHead = child.$$childTail = null;
         child.$$prevSibling = this.$$childTail;
         if (this.$$childHead) {
           this.$$childTail.$$nextSibling = child;