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Firefox really slow, consuming too much CPU, tried everything

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  • 46 have this problem
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  • Last reply by Happy112

Johan Hartmann
Johan Hartmann
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Alright so I was testing out Avira Phantom VPN and installed it, which included the Avira Connect app and the Avira Browser Security plugin.

Then I restarted Firefox and it started working slow as hell and consuming way too much CPU, 10-25% when idle. It's literally unusable at the moment.

I tried rebooting my computer, didn't fix it.

Uninstalled all Avira software, still slow and consuming too much CPU.

Started Firefox in Safe Mode where it works fine, and removed the Avira plugin, nothing.

Then I disabled all the plugins, no changes, still slow.

Then I uninstalled Firefox and reinstalled it, no effect.

Ran Firefox in Safe Mode again and removed the "content-prefs.sqlite" file incase it was corrupt. Nothing.

In Safe Mode I tried to Refresh Firefox, it had no effect.

I uninstalled it again, and ran CCleaner to clear out any temporary files and registry entries that might be causing problems. Reinstalled it as 64-bit instead of the default 32-it, and I'm still having the same problems.

Any suggestions?

Alright so I was testing out Avira Phantom VPN and installed it, which included the Avira Connect app and the Avira Browser Security plugin. Then I restarted Firefox and it started working slow as hell and consuming way too much CPU, 10-25% when idle. It's literally unusable at the moment. I tried rebooting my computer, didn't fix it. Uninstalled all Avira software, still slow and consuming too much CPU. Started Firefox in Safe Mode where it works fine, and removed the Avira plugin, nothing. Then I disabled all the plugins, no changes, still slow. Then I uninstalled Firefox and reinstalled it, no effect. Ran Firefox in Safe Mode again and removed the "content-prefs.sqlite" file incase it was corrupt. Nothing. In Safe Mode I tried to Refresh Firefox, it had no effect. I uninstalled it again, and ran CCleaner to clear out any temporary files and registry entries that might be causing problems. Reinstalled it as 64-bit instead of the default 32-it, and I'm still having the same problems. Any suggestions?

Chosen solution

Hi   ! Are you by any chance running Bitdefender Anti-virus  ? If so, you may want to disable it   -   see this bug that was just reported :
https://bugzilla.mozilla.org/show_bug.cgi?id=1363317
According to your system details you are using the Multiprocess feature, which might be causing this problem as well.

You could turn it off as follows : Type in the address bar about:config (promise to be careful, if asked) Type and search for the preferences : browser.tabs.remote.autostart and set it's value to false browser.tabs.remote.autostart.2 and set it's value to false Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

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All Replies (1)

Happy112
Happy112
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Chosen Solution

Hi   ! Are you by any chance running Bitdefender Anti-virus  ? If so, you may want to disable it   -   see this bug that was just reported :
https://bugzilla.mozilla.org/show_bug.cgi?id=1363317
According to your system details you are using the Multiprocess feature, which might be causing this problem as well.

You could turn it off as follows : Type in the address bar about:config (promise to be careful, if asked) Type and search for the preferences : browser.tabs.remote.autostart and set it's value to false browser.tabs.remote.autostart.2 and set it's value to false Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart