1179832 - CSS/SVG animation on /firefox/desktop performance regression in Firefox

Status: RESOLVED WORKSFORME

(Core :: SVG, defect)

Description

[Alex Gibson [:agibson]]

"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:40.0) Gecko/20100101 Firefox/40.0"

We've had the following CSS/SVG animation up on the Firefox for Desktop page for some time. It started off pretty smooth when we made it, but recently has not been performing in Firefox as well as other browsers.

https://www.mozilla.org/en-US/firefox/desktop/

In Firefox 40 and upward (so current dev edition or nightly), there seems to be some form of recent performance regression. The animation starts off smoothly, but toward the end there is some considerable jank when the browser image moves downward to reveal the text. Just guessing, but this might be related to recent changes to off-main-thread animations perhaps?

I would love to see this animation on par with other browsers. Chrome, Safari and Opera all render it pretty smooth.

Happy to try and help diagnose / answer questions.

Comment 1

[Daniel Holbert [:dholbert]]

Thanks for the report -- if you can use the "mozregression" tool to isolate a nightly regression range, that'd be extremely helpful to determine what caused the breakage.

mozregression available here:
  http://mozilla.github.com/mozregression/

If you're sure this broke in Firefox 40, you could try:
  mozregression --good 2015-03-25 --bad 2015-05-15

(That time range spans the period when mozilla-central/nightly was version 40, with a few days of padding on each end.)

Comment 2

[Alex Gibson [:agibson]]

I can try, but I'm not actually sure when the regression occurred - it may have been longer. There seems to have been a lot of change between Firefox 39 and 40 in regard to OMTA, so it's hard to visually pick out what changes and when.

Comment 3

[Daniel Holbert [:dholbert]]

OK, yeah -- subtle perf bugs can be difficult (or impossible) to confidently track down w/ mozregression; that might turn out to be the case here (and it sounds like you may want to broaden the time window, if you do try to track it down).

FWIW, the animation looks quite smooth in current Nightly 42.0a1 (2015-07-01) on my linux laptop. So, this might be a mac-specific issue, given that you're on a mac.

Comment 4

[Alex Gibson [:agibson]]

Still trying to disgnose when things get funky, but when running mozregression I did noticed this:

"Performance warning: Async animation disabled because frame size (1880, 862) is bigger than the viewport (1215, 617) or the visual rectangle (1880, 862) is larger than the max allowable value (17895698) [div with id 'intro-svg-anim']"

Comment 5

[Alex Gibson [:agibson]]

Since I opened this bug, performance in Nightly seems to have improved significantly. Going to close this for now, but will re-open if I start to see issues again. Thanks!

Comment 6

[Robert Longson [:longsonr]]

Almost certainly because of the landing of the patch for bug 1171966