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What causes Firefox to Hog cpu?

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Have recently purchased new computer running windows 10. Firefox is using extreme cpu. 100% most of the time and seldom less than 20%. To use computer have to shutdown Firefox. Have just installed Google Chrome and it behaves as you would expect. Seldom over 80% and dropping to nil. So problem is within Firefox. Prefer to use iot but currently unworkable.

Have recently purchased new computer running windows 10. Firefox is using extreme cpu. 100% most of the time and seldom less than 20%. To use computer have to shutdown Firefox. Have just installed Google Chrome and it behaves as you would expect. Seldom over 80% and dropping to nil. So problem is within Firefox. Prefer to use iot but currently unworkable.

All Replies (10)

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What's your computer system and Firefox version?

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options)
key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?


https://support.mozilla.org/en-US/kb/firefox-slow-how-make-it-faster

https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix

https://support.mozilla.org/en-US/kb/firefox-hangs-or-not-responding

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Windows 10. Firefox 32 bit. Updated yesterday. Problem there before and after update. Have tried safe mode - no difference. Shutting down Firefox and restarting it sometimes solves problem but it generally returns in time. I am doing this with Chrome which works as you would expect - Firefox unworkable.

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Does the about:performance page give you any suspects?

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What 'about:performance page' would that be? More info Pls.

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Type "about:performance" no quotes in the awesomebar.

It looks like this https://cdn.ghacks.net/wp-content/uploads/2015/08/firefox-performance-monitor.jpg

Do you see anything in red or orange?

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No. Blames 2 unread emails using about 8% when FF is chewing 60+% (all that is available).

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Sorry, The 2 unread emails were in red. Tried opening a few other tabs/pages but makes little difference. No explanation for chewing all available cpu.

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Well I guess no one cares. Not happy about it but have changed to Google Chrome.

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Start your Computer in safe mode with networking. Then start Firefox. Try Safe websites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

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Can you post your Firefox troubleshooting information.

What security software do you have?


Create a new profile to test if your current profile is causing the problem.

See "Creating a profile":

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

You can check for issues caused by plugins.

  • set plugins to "Ask to Activate" on the about:addons page ("3-bar" menu button or Tools -> Add-ons -> Plugins)
  • plugins are not affected by Firefox Safe Mode