1799681 - Bringing firefox to the foreground when another application has focus results in a short freeze

Status: UNCONFIRMED

(Core :: Widget: Cocoa, defect, P3)

Description

[Max Maton]

Attachment: Profile captured while switching to another application and then back

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:106.0) Gecko/20100101 Firefox/106.0

Steps to reproduce:

• Run firefox on mac
• Leave running for a long time
• Press command+tab to switch to other application
• Press command+tab to switch back to firefox

(see attached profile)

Actual results:

Firefox freezes for a few seconds before becoming interactive.

Expected results:

Switching firefox to the foreground should be near instant

Comment 1

[Max Maton]

I've found other people that may have experienced the same problem:

• https://www.reddit.com/r/firefox/comments/xwlpxy/on_macos_commandtab_switching_to_firefox_lags/
• https://www.reddit.com/r/firefox/comments/qr15hb/switching_to_firefox_with_commandtab_on_mac_has_a/

Comment 2

[Max Maton]

The entire freeze time (1 second) seems to be spent on the main thread in [NSApplication setMainMenu:]

Comment 3

[Peter Magyari (Desktop QA)]

Hi Max,

I wasn't able to reproduce this issue on MacOS 11.6, however, I'm going to set a component in order to get this looked at by the development team.

Meanwhile, could you please check if this also occurs on Firefox Nightly?
You can get it from here: https://www.mozilla.org/en-US/firefox/108.0a1/releasenotes/

Thanks!

Comment 4

[Max Maton]

I'll leave nightly open for a while to see if I can reproduce it there.

It might have something to do with the fact that my mac has a notch and runs raycast. Both of which use up a lot of menu bar space.

Comment 5

[Max Maton]

Attachment: Profile in firefox nightly after 24 days of runtime while switching applications

The hang on nightly seems to be less severe. Not sure if that's due to any changes or due to me using it less.

Attached is the profile for switching focus for nightly. It also spends a lot of time in [NSApplication setMainMenu:]