1247510 - Constant lags while autoscrolling on gaming.youtube.com

Status: RESOLVED WORKSFORME

(Core :: Layout, defect)

Description

[arni2033]

>>>   My Info:   Win7_64, Nightly 46, 32bit, ID 20160209030347
STR:
1. Open https://gaming.youtube.com/watch?v=gCISR0T3grE
2. Wait until the page is loaded
3. Autoscroll the left block (containing the video)

AR: there're very noticeable lags every second
ER: No lags, just like on GoogleChrome

Note:
1) This behavior is presented on Firefox 36+, and that site doesn't work on earlier versions
2) Probably it'll be fixed with APZ, but sometimes APZ just hides cases when Firefox overuses
   CPU/RAM, so this still may be useful
3) In Profiler, I see that FPS drops to ~2 when I autoscroll. Actually, it drops to ~2 anyway, no
   matter if I autoscroll or scroll with mouse option "scroll by 1 page" with APZ enabled/disabled.
4) Actually, when I use profiler in GoogleChrome, I still see that it's being busy, but
    less than Firefox. It seems that firefox is loosing in requestAnimationFrame performance.
   So while the bad performance is clearly a fault of gaming.youtube.com developers, that site
    still may be used as a test case of requestAnimationFrame slowness. Just thinking aloud.
Here's approximate screenshot of Profiler for Note (4):
> https://dl.dropboxusercontent.com/s/gdlkj80g579dhft/screenshot%201%20-%20Browser%20hangs%20after%20clicking%20on%20a%20specific%20record%20in%20Waterfall.png?dl=0

Comment 1

[arni2033]

>>>   My Info:   Win7_64, Nightly 49, 32bit, ID 20160526082509
Currently there are no issues with performance on that site.
It was fixed on their side, so the site couldn't be used as a testcase.