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Just installed Firefox on Windows XP. It is chewing up 99% of CPU? Unusable! Going back to Chrome.

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Cannot do anything. Cannot get to turn off the plugins as I cannot do anything with Firefox using 99% of CPU the hourglasss is controlling the process.

Cannot do anything. Cannot get to turn off the plugins as I cannot do anything with Firefox using 99% of CPU the hourglasss is controlling the process.

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Hi teddybrie, In order to minimize the amount of CPU used when browsing with Firefox please also see: Fix Firefox using too much memory or CPU resources

Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?

Then restart.

cannot do anything once Firefox starts - hogs up 99% of CPU with hour glass on the screen. How do you start it in Safe mode when it does not let you do anything????? I used to love Firefox. Something changed!

Start Firefox in Safe Mode by holding down the <Shift(Mac Options)> key, and then starting Firefox.

You can try to disable OMTC and leave hardware acceleration in Firefox enabled.

  • about:config page: layers.offmainthreadcomposition.enabled = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.