Join the Mozilla’s Test Days event from 9–15 Jan to test the new Firefox address bar on Firefox Beta 135 and get a chance to win Mozilla swag vouchers! 🎁

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Mulongo oyo etiyamaki na archive. Tuna motuna mosusu soki osengeli na lisalisi

Firefox using 200% CPU on 8-core mac, with NO tabs open

  • 1 eyano
  • 1 eza na nkokoso oyo
  • 1 view
  • Eyano yasuka ya india42

india42
india42
more options

Early 2011 MBP 17", macOS 10.12.1, Firefox 50.0.2

When I open Firefox, the %CPU in Activity Monitor jumps to over 200% immediately (8-core CPU) and jumps higher if I open any tabs. The core temperatures, as reported by iStat Menus, are all over 90° C, even with the fans set to max RPM.

I've shutdown every plug-in, add-on and extension, but the behaviour does not change.

Why is Firefox using so much CPU resource when it is essentially idling? How can I stop this?

Early 2011 MBP 17", macOS 10.12.1, Firefox 50.0.2 When I open Firefox, the %CPU in Activity Monitor jumps to over 200% immediately (8-core CPU) and jumps higher if I open any tabs. The core temperatures, as reported by iStat Menus, are all over 90° C, even with the fans set to max RPM. I've shutdown every plug-in, add-on and extension, but the behaviour does not change. Why is Firefox using so much CPU resource when it is essentially idling? How can I stop this?

All Replies (1)

india42
india42 Nkolo motuna
more options

I forgot to mention. There are a lot of threads as well.