Created attachment 766896 [details] interactive testcase 01 User Agent: Mozilla/5.0 (Windows NT 5.1; rv:24.0) Gecko/20130624 Firefox/24.0 (Nightly/Aurora) Build ID: 20130624031040 Steps to reproduce: When animated box exceeds body edge all elements in body are being repainted. Actual results: "paintflashing on" while animated element crosses body boundary plays heavy disco. (Play with attachment.) Expected results: No repaints for animated element (partially or completely) outside body, like it is already for element completely inside body.
Confirmed on Nightly 24 & stable 22, 21 @ Win XP, 7, 8, various integrated Intel GMA graphics or AMD Radeons. Tried on Ubuntu 13.04 on old Celeron M with Intel "915GM" graphic: cannot tell about repaints exactly (developer's tools lacks paintflashing here) but from CPU graph it seems quite opposite: CPU load _drops_ from 100 % to 60 % during animated elements and body intersections. Interesting. Possibly related: Bug 652397
Confirmed on Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:22.0) Gecko/20100101 Firefox/22.0 @ Kubuntu 12.04.
I can reproduce this bug using Windows 7 64-bit and the latest Nightly.
Todays Fx 26 and recent Nightlies (Win 7, Win 8.1) do not show described behaviour anymore. So if it isn't the paintflashing mechanism what changed this bug seems fixed to me. Could anyone recheck this on different platform / GPU? Mozilla/5.0 (Windows NT 6.1; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0
Marking as resolved: bug haven't occurred since 26 for me (both with and without layers.acceleration.disabled), and apparently no other complaint appeared since then.