Closed Bug 1794582 Opened 1 year ago Closed 5 months ago

After update, Firefox uses copious amounts of CPU while being idle.


(Core :: Performance, defect)

Firefox 104





(Reporter: herth, Unassigned, NeedInfo)


User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:105.0) Gecko/20100101 Firefox/105.0

Steps to reproduce:

Updated Firefox

Actual results:

Starting with 104 but also on 105, after performing an update of Firefox, the restarted Firefox uses a lot of CPU (60%-200%) without any activity or obviously busy tabs. This lasts for many and only very gradually goes down. Even after several days, the browser creates a "base" cpu load of 30%. This has been observed using several different machines, x86 and ARM, OS versions ranging from Mojave to Monterrey.

Expected results:

After restart, the CPU load should be very small.

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

Component: Untriaged → Performance
Product: Firefox → Core

Sorry to hear you are having problems after the update, this slowness is unexpected and undesirable and we would like to fix it. We are trying to track down this issue, but need more info from you about your machine and configuration.

Could you make sure the following information is on this bug?

  • For slowness or high CPU usage, capture a profile with , upload it and share the link here.
  • For processes and activity usage issues, Got to about:processes and screen shot what you see, upload it to this bug report.
  • Troubleshooting information: Go to about:support, click "Copy raw data to clipboard", paste it into a file, save it, and attach the file here.

Thank you.

Flags: needinfo?(herth)

With no answer from the reporter, we don’t have enough data to reproduce and/or fix this issue. Please reopen or file a new bug with more information if you see it again.

Closed: 5 months ago
Resolution: --- → INCOMPLETE
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