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Why is the latest version of Firefox 33.0.2 using 100% of my CPU?

  • 4 replies
  • 2 have this problem
  • 23 views
  • Last reply by Wayne Mery

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Just like the last update to Thunderbird, with no changes on my system, the latest version of Firefox uses 100% of my CPU where it didn't before. I've run every test, disabled my anti-virus, run in safe mode and it makes no difference.

Since there was no useful answers when I posted about the TB problem, I doubt there will be any here.

Sorry Mozilla, but you're about to lose my support. I already moved away from Thunderbird. Now that FF has the same problem, I'm about to switch my browser to Chrome, even though it is not as good.

All Replies (4)

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Hello DrStrange You can try to disable hardware acceleration in Firefox.

   Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available" 

You need to close and restart Firefox after toggling this setting.

   https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes
   https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration
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I already have hardware acceleration in FF unchecked, so that doesn't help.

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Create a new profile as a test to check 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.

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  1. 1 install flashblock addon
  2. 2 see https://developer.mozilla.org/en-US/docs/Mozilla/Performance/Profiling_with_the_Built-in_Profiler and post the URL of a short profile