RESOLVED INVALID44173
Scrolling is slow and stuttery on some long pages (due to accelerated compositing?) 
https://bugs.webkit.org/show_bug.cgi?id=44173
Summary Scrolling is slow and stuttery on some long pages (due to accelerated composi...
Adam Roben (:aroben)
Reported 2010-08-18 06:48:35 PDT
To reproduce: 1. Open the attached Web Archive 2. Drag the scrollbar down to the bottom When you reach about 2/3 of the way down the page (in the middle of the "Storport ETW Logging to Measure Requests Made to a Disk Unit" article), scrolling becomes slow and stutters. The scroll thumb visibly lags behind the mouse. I've only tested with Safari 5.0.1 on SnowLeopard.
Attachments
testcase (3.32 MB, application/x-webarchive)
2010-08-18 06:49 PDT, Adam Roben (:aroben) 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Adam Roben (:aroben)
Comment 1 2010-08-18 06:49:07 PDT
Created attachment 64701 [details] testcase
Adam Roben (:aroben)
Comment 2 2010-08-18 07:08:08 PDT
<rdar://problem/8324086>
Adam Roben (:aroben)
Comment 3 2010-08-18 09:46:24 PDT
Here's an even easier to reproduce case: 1. Go to http://trac.webkit.org/browser/trunk/WebKit/win/WebView.cpp?rev=58900#L946 2. Drag the scroll bar thumb Scrolling is horribly slow. Tiles of the page visibly repaint as you go. Turning off accelerated compositing brings performance back to acceptable levels.
Adam Roben (:aroben)
Comment 4 2010-08-18 09:54:00 PDT
Whoops, I had an extension installed that turned on accelerated compositing for all <img> elements. Without that extension these pages don't go into accelerated compositing mode. Simon Fraser assures me that we already have bugs that cover the symptoms I was seeing on pages that legitimately use accelerated compositing, so I'm going to close this bug.
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