From 341a28402df2e7e8a4e73c8a7cd440301cf37732 Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Tue, 20 Aug 2013 10:35:02 +1000
Subject: [PATCH] speed up scrolling on android

---
 .../javascripts/discourse/views/topic_view.js     | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/app/assets/javascripts/discourse/views/topic_view.js b/app/assets/javascripts/discourse/views/topic_view.js
index b07c638cac..176cf6060a 100644
--- a/app/assets/javascripts/discourse/views/topic_view.js
+++ b/app/assets/javascripts/discourse/views/topic_view.js
@@ -25,10 +25,19 @@ Discourse.TopicView = Discourse.View.extend(Discourse.Scrolling, {
   }.observes('controller.streamPercentage'),
 
   updateProgressBar: function() {
-    var $topicProgress = $('#topic-progress');
-    if (!$topicProgress.length) return;
+    var $topicProgress = this.topicProgress;
 
-    var totalWidth = $topicProgress.width();
+    // cache lookup
+    if (!$topicProgress) {
+      $topicProgress = $('#topic-progress');
+      if (!$topicProgress.length) {
+        return;
+      }
+      this.topicProgress = $topicProgress;
+    }
+
+    // speeds up stuff, bypass jquery slowness and extra checks
+    var totalWidth = $topicProgress[0].offsetWidth;
     var progressWidth = this.get('controller.streamPercentage') * totalWidth;
 
     $topicProgress.find('.bg')