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High cpu usage and intermitten freezes.

  • 8 cavab
  • 1 has this problem
  • 1 view
  • Last reply by nicolaj82

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Using x64 and usually have between 10 & 20 tabs open at all times. Even if there is no active content on the open sites, i often experience that when opening a new tab, loading a new page freezes firefox completely for up to 10 secs. And i also sometimes experience really high cpu usage, like 30/40%.

I have ublock & lastpass. Those are the only 2 plugins that are always on. I'm assuming it's a bug in firefox as i expect having 10 tabs open should not make it break a sweat. Now i don't mind it using 1.5gb of my memory as i have 16gb. Do you have any suggestions on tweaks or tips i could do. Or how i would possibly diagnose the problem so i could report it?

Using x64 and usually have between 10 & 20 tabs open at all times. Even if there is no active content on the open sites, i often experience that when opening a new tab, loading a new page freezes firefox completely for up to 10 secs. And i also sometimes experience really high cpu usage, like 30/40%. I have ublock & lastpass. Those are the only 2 plugins that are always on. I'm assuming it's a bug in firefox as i expect having 10 tabs open should not make it break a sweat. Now i don't mind it using 1.5gb of my memory as i have 16gb. Do you have any suggestions on tweaks or tips i could do. Or how i would possibly diagnose the problem so i could report it?

All Replies (8)

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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?

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I ran with it for a few hours, and didn't notice anything. But that said it is kinda hard as i can run for an entire day without issues only to experience it once at the end of the day. Or maybe not at all.

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Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). If the problem goes away, that tells us one thing. If it does not, that tells us something else.


It could be the work of one of your add-ons. Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac=<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.

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So basically just disable ublock and lastpass ? One thing tho, since ublock can block hundreds of items on a page, shouldn't that in essence require less resources as these aren't displayed. So by disabling it, firefox should in theory use more resources?

Modified by nicolaj82

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nicolaj82 said

So basically just disable ublock and lastpass ?

You can start with them if you want. It's only temporary, so don't worry.

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FredMcD said

You can start with them if you want. It's only temporary, so don't worry.

What do you mean "start with them". Are there supposed to be other options there i don't know about ?

Modified by nicolaj82

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FredMcD said

Disable a few add-ons, then Restart Firefox.

If the problem continues, disable some more (restarting FF)
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Ok. For a sec there you had me confused. So just disable ublock and lastpass and run with it for a day or two. I already know that i'm going to hate it :P