1452622 - Large restyle on window activation on OSX.

Status: RESOLVED WORKSFORME

(Firefox :: General, enhancement, P3)

Description

[Emilio Cobos Álvarez [:emilio]]

See the profile in bug 1452525 comment 7. With that bug fixed, we'd spend ~70ms on window activation, where we only re-selector-match 23 elements, but we restyle 11k+.

That restyle is caused due to a CSS variable change in:

  https://searchfox.org/mozilla-central/source/browser/themes/osx/browser.css#147-149

In particular, that causes the whole tab stripe to be recascade, because the properties need to be inherited.

This would get improved on our side by bug 1417970 (https://github.com/servo/servo/pull/20151), but seems worth fixing regardless whether that optimization lands.

Comment 1

[Xidorn Quan [:xidorn] UTC+10]

The improvement of bug 1417970 is unlikely to be upliftable, because it's rather risky, so if we do care about the restyle shows up in bug 1452525 in beta, we may want to do something in the frontend... I'm not sure how bad that is, though.

Comment 2

[:Gijs (he/him)]

Bit tricky without permalinks but I think comment 0 is pointing to https://searchfox.org/mozilla-central/rev/8904c372ca4cf110676be6e0d5626189a31d6e3b/browser/themes/osx/browser.css#142-145 - bug 1673321 removed these styles so I think this should be wfm. If not, let's clarify what is still causing issues here.