1820916 - CPU usage spikes to ~90% during window switching on MacOS after Firefox has been open for a few hours.

Status: RESOLVED DUPLICATE of bug 1808223

(Core :: Widget: Cocoa, defect)

Description

[douglasaaser]

Attachment: 23-03-07-ka7hw.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/110.0

Steps to reproduce:

MacOS Ventura 13.2.1 - M1 Pro chip
After having Firefox open for ~4.5 hours I am seeing large CPU spikes when switching between windows. Specifically it happens when switching to Firefox, either from another window within Firefox or another application.

Actual results:

I ran the profiler and grabbed was able to see that every time I switched windows there was a ~1s CPU burst: https://share.firefox.dev/3yiX4oD
In the attached picture you can see that the main Firefox process is only using <5% of my total CPU time. This issue resolves itself when I completely exit the Firefox process and restart it. I tried disabling a few extensions which didn't help. This issue seems like either a memory leak or some sort of lock contention issue but I don't understand the code base enough to offer up anything more.

Expected results:

Firefox should render immediately and not take 1s or spike CPU ~90%

Comment 1

[BugBot [:suhaib / :marco]]

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Cocoa' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Stephen A Pohl]

This is a duplicate of bug 1808223 and on my radar.