User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0 Build ID: 20121024073032 Steps to reproduce: I tried to access www.negden.com. Actual results: Html5 animation was really slow compared to Chrome and IE9 (1/2 less frames). Checking the about:support, I discover 2d acceleration was 'locked for my driver'. So I downloaded, installed the new drivers, rebooted but flags still say 2d acceleration is off. flags screenshot attached Expected results: 2d acceleration shall have been supported on ati hd5700. Earlier versions of firefox used to support it..

On Windows 7 for AMD/ATI GPUs, we require Catalyst 10.6 or higher except 12.8: https://wiki.mozilla.org/Blocklisting/Blocked_Graphics_Drivers It might be blocked for HW reasons. Does it works if you force it by setting gfx.direct2d.force-enabled to true (Firefox restart required)?