1839037 - All tabs list excruciatingly slow

Status: VERIFIED FIXED

(Firefox :: Tabbed Browser, defect)

Description

[bintoro]

The "Show all tabs" list has become really sluggish after upgrading to 115.0b, perhaps due to bug 1620199. The highlighted row follows the mouse cursor with a lag, and scrolling the list is unbearably slow.

Comment 1

[Dão Gottwald [:dao]]

(In reply to bintoro from comment #0)

The "Show all tabs" list has become really sluggish after upgrading to 115.0b, perhaps due to bug 1620199.

A narrowed down regression range might be useful here.

Comment 2

[Cieara Meador [:cmkm]]

(In reply to bintoro from comment #0)

The "Show all tabs" list has become really sluggish after upgrading to 115.0b, perhaps due to bug 1620199. The highlighted row follows the mouse cursor with a lag, and scrolling the list is unbearably slow.

Hello! Thank you for raising this concern. If possible, would you be willing to please share a profile to help us narrow this down? You can find instructions here.

Comment 3

[Mike Conley (:mconley) (:⚙️)]

I think I was able to reproduce this on my Macbook. I captured some profiles:

With close button: https://share.firefox.dev/44krQLR
With close button hidden: https://share.firefox.dev/44jpvAN

It looks like in both cases we're doing main thread fallback painting... and it gets a lot more expensive for some reason with the close button visible.

Hey mstange, any idea why this change would cause painting while scrolling the tab manager panel to become so expensive?

Comment 4

[Markus Stange [:mstange]]

Does the button have an opacity? We might be hitting a slow path where we create an intermediate surface the size of the popup for every close button. Removing the opacity might work as a workaround.

There's a patch which would most likely fix all the slow drawing in this panel in bug 1754796, but it caused test failures which need to be debugged.

Comment 5

[Mike Conley (:mconley) (:⚙️)]

Yes! There does appear to be an opacity: https://searchfox.org/mozilla-central/rev/926b6c9fc7d84b603f501448c31d489473862bca/browser/themes/shared/tabs.css#776

cmkm, is this opacity a hard design requirement? Or do you think we can either remove it or achieve the appearance in a different way?

Comment 6

[Cieara Meador [:cmkm]]

(In reply to Mike Conley (:mconley) (:⚙️) from comment #5)

Yes! There does appear to be an opacity: https://searchfox.org/mozilla-central/rev/926b6c9fc7d84b603f501448c31d489473862bca/browser/themes/shared/tabs.css#776

cmkm, is this opacity a hard design requirement? Or do you think we can either remove it or achieve the appearance in a different way?

Confirmed with UX that we can eliminate the opacity rule for the time being, going to get a patch up to do so for this ticket. We can reinstate the opacity rule with bug 1820171, hopefully.

Comment 7

[Cieara Meador [:cmkm]]

Attachment: Bug 1839037 - Remove tab manager button opacity to prevent slowdown r?mhowell,dao

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f7f4f7480ce8
Remove tab manager button opacity to prevent slowdown r=mhowell

Comment 9

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/f7f4f7480ce8

Comment 10

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:cmkm, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox115 to wontfix.

For more information, please visit BugBot documentation.

Comment 11

[Cieara Meador [:cmkm]]

Comment on attachment 9341388 [details]
Bug 1839037 - Remove tab manager button opacity to prevent slowdown r?mhowell,dao

Beta/Release Uplift Approval Request

• User impact if declined: Users with many tabs (100+ estimate) will experience slowdown in the Tab Manager
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce:
  1. Open many tabs
  2. Open the Tab Manager (Caret in tabstrip next to new tab button)
  3. Verify hover and scroll responsiveness are within normal expectations
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Not risky, removing a single CSS rule
• String changes made/needed: n/a
• Is Android affected?: No

Comment 12

[Donal Meehan [:dmeehan]]

Comment on attachment 9341388 [details]
Bug 1839037 - Remove tab manager button opacity to prevent slowdown r?mhowell,dao

Fx115 is now in RC, switching to a release uplift request

Comment 13

[Cieara Meador [:cmkm]]

(In reply to Donal Meehan [:dmeehan] from comment #12)

Comment on attachment 9341388 [details]
Bug 1839037 - Remove tab manager button opacity to prevent slowdown r?mhowell,dao

Fx115 is now in RC, switching to a release uplift request

Thanks Donal, sorry about that!

Comment 14

[Donal Meehan [:dmeehan]]

Comment on attachment 9341388 [details]
Bug 1839037 - Remove tab manager button opacity to prevent slowdown r?mhowell,dao

Approved for 115.0 RC2

Comment 15

[Donal Meehan [:dmeehan]]

https://hg.mozilla.org/releases/mozilla-release/rev/cd136ea0f8c2

Comment 16

[Daniel Bodea [:danibodea]]

I have reproduced this issue on MacBook Air 2013 and Firefox Beta v115.0b6 and Nightly v116.0a1 (2023-06-16).
Furthermore, I could verify the fix in Nightly v116.0a1 (2023-06-29). We will verify in branch 115 when possible.

Comment 17

[Donal Meehan [:dmeehan]]

https://hg.mozilla.org/releases/mozilla-esr115/rev/2a25b7a2761e

Comment 18

[Daniel Bodea [:danibodea]]

The fix is also confirmed in Beta v115.0 (RC) on the same machine. THank you.