From Ana Tudor (@thebabydino), who uses Firefox again but still runs demos during talks in Chrome. She says """ 1. 3D. Example http://codepen.io/thebabydino/pen/yehGi animation is slightly choppy, brings CPU at 30-50% vs 5-8% for Chrome (7.5 year old Sony VAIO, Windows 7) The way elements are displayed on top of the other is not always determined by the 3D positioning and I can't even find a pattern for this. I guess animation in general, not just 3D. Gets obvious when taken to the extreme with animating hundreds of things at the same time. """ The second and third paragraphs may be other bugs, or this could be a tracking bug based on concrete bugs filed against her codepen.io demos, starting with http://codepen.io/thebabydino/pen/yehGi Giving to Vlad to avoid unowned status from start. /be

We'll contact Ana to get the specs for her system; on a Windows 7 desktop I have, this uses ~ 3% CPU. On a Macbook Pro, ~6% CPU. We're probably hitting the software path on her system, and if Chrome is not, it's most likely that we have her driver or system blacklisted. The second paragraph at first looks like standard z-fighting, I see it on both systems I tried it on. It may not be just that though, but either way it may eventually need a separate bug.

Cloned the correctness part to bug 937137. Bas is seeing the jank and higher CPU usage on his system, so assigning to him.

Hmm. I don't fully trust my eyes, so it's worth a profile, but I want to say that I can see some jank on Win 7 in nightly 28, where I don't see it in the released 25.

Any news? /be

(In reply to Brendan Eich [:brendan] from comment #4) > Any news? > > /be No investigation has been done on this bug, let me know if this is high priority.

On the CSS transform animation performance and correctness side, there is some work being done in bug 931668, bug 977991, bug 960465.