Build Identifier: http://hg.mozilla.org/releases/mozilla-release/rev/2b643ea8edf9 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20100101 Firefox/13.0 ID:20120601045813 I notice a problem when I test Bug 763504. Steps to Reproduce: 1. Create clean profile 2. Open http://docs.sencha.com/ext-js/4-1/#!/example/grid/array-grid.html 3. Try to scroll the table with hold mouse down scroll arrow "aaaa".match('//b[@class="powered-by"]/a[contains(@href, "sites.google.com")]') Actual Results: Scroll is very slow, scroll amount is very little. Expected Results: Scroll should be performed as same as before Regression window: Good: http://hg.mozilla.org/mozilla-central/rev/047c8ba7d2e4 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0a1) Gecko/20120115 Firefox/12.0a1 ID:20120115112312 Bad: http://hg.mozilla.org/mozilla-central/rev/a895ecb782e1 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0a1) Gecko/20120116 Firefox/12.0a1 ID:20120116022308 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=047c8ba7d2e4&tochange=a895ecb782e1 Triggered by: f7c8c8ee3fad Jared Wein — Bug 198964 - Enable smooth scrolling by default. r=gavin However, this problem existed in earlier version if smooth scroll enabled.

please ignore a line in comment #0 > "aaaa".match('//b[@class="powered-by"]/a[contains(@href, "sites.google.com")]')

I wonder if this has the same cause as bug 726468.