From 20a75ac983293557a7e5b3ddb5dba30b189e67d6 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Sat, 9 May 2015 14:57:42 -0700
Subject: [PATCH] Performance improvement for iD.Difference

Avoid creating lots of unnecessary temporaries by short circuiting in a
common case.
---
 js/id/core/difference.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/js/id/core/difference.js b/js/id/core/difference.js
index 6e46feb78..9f95846b5 100644
--- a/js/id/core/difference.js
+++ b/js/id/core/difference.js
@@ -10,7 +10,7 @@ iD.Difference = function(base, head) {
     var changes = {}, length = 0;
 
     function changed(h, b) {
-        return !_.isEqual(_.omit(h, 'v'), _.omit(b, 'v'));
+        return h !== b && !_.isEqual(_.omit(h, 'v'), _.omit(b, 'v'));
     }
 
     _.each(head.entities, function(h, id) {