1716686 - Big tables jank the browser hard [with dark-background-light-text addon]

Status: NEW

(Core :: Layout: Tables, defect)

Description

[Paul Bone [:pbone]]

https://profiler.firefox.com/public/prqh8wg7mdnq450bjj1m1qsa0br3k1cszkjk0fg/stack-chart/?globalTrackOrder=0&localTrackOrderByPid=196295-0-1~&thread=0&timelineType=cpu-category&v=5

Opening: https://hg.mozilla.org/mozilla-central/firefoxreleases#bbb448a557b4nightlylinux3220210531170022 janks the browser badly, see the above profile.

Comment 1

[Olli Pettay [:smaug][[e-mail]]]

I can't reproduce, but could this be related to the other recent hangs people have seen (Like bug 1713170)

Paul, if you can reproduce this, do you know if this is a recent regression?

Comment 2

[Paul Bone [:pbone]]

Maybe a regression, because it's better when I tested it today. I see the page appear and as I scroll around I find big unfilled areas that take maybe 20 seconds before they fill in with data, other than that scrolling continues to be smooth. When I found this bug the scrolling was not smooth, and I think it affected tab switching also.

It could also be an extension I run that caused the problem, https://addons.mozilla.org/en-US/firefox/addon/dark-background-light-text/, since it changes the styling of pages and may have "changed" performance. I don't know though, but it's another factor that may be involved.

Is it supposed to not fill the table for multiple seconds while it's loading? I don't know if that's how the web/browsers are supposed to work, if that's okay we can close the bug. I may need to make a video.

Comment 3

[Emilio Cobos Álvarez [:emilio]]

It is also pretty fast here. I'd say it's unrelated to bug 1713170 (that's parent-process only, and seems to be caused by the profiler collecting chrome-js stacks).

I installed the extension mentioned in comment 2 and could notice quite a massive restyle indeed. Paul, can you confirm it doesn't repro without that extension?

Still it's worth looking into (either the extension is doing something dumb, or we could probably optimize some of what it is doing away).

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

I guess this is waiting for an answer to the question in comment 3.

Comment 5

[Paul Bone [:pbone]]

I think there's more than one problem. This janks bad with the above addon:
https://share.firefox.dev/3tXp3IA

It janks a little bit without the addon but with accessability still enabled, but in a different part of code. So I think this is a different problem, spun off in Bug 1802268:
https://share.firefox.dev/3EyGmED

It is smooth if I set accessibility.force_disabled = 1
https://share.firefox.dev/3Er3ViE