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firefox lagging due to high cpu usage

  • 6 replies
  • 1 has this problem
  • 88 views
  • Last reply by creash

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Hi all,

I've been having problems with firefox lagging constantly. General browsing around feels laggy - and opening new tabs pretty much causes my computer to freeze for a few seconds. During this time firefox causes the CPU to spike to 100% usage.

I've been using firefox for years on this computer with no issues. Hardware is pretty good (i7 5820k, 64GB of ram and an SSD).

So far I have tried:

  • Running in safe mode
  • Using a different profile
  • Downgrading to an older firefox
  • Changing allowed CPU cores from 8, to 4
  • Updated graphic card drivers to latest version

None of these work, and I'm getting a bit tired of the constant slow downs. Chrome works flawlessly, as does all my other software...

Any ideas?

Thanks!

Chosen solution

Hello!

After digging into the CPU usage indepth, it turns out that it wasn't firefox at all... it was malwarebytes!

As soon as I closed MB, bam, firefox works flawlessly again.

Thanks for the help!

Read this answer in context 👍 1

All Replies (6)

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Enter about:support in the URL bar and examine the Graphics section. There should be Webrender in the first row.

Helpful?

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Hi,

Thanks for the reply.

Yes webrender is there in the first row.

Helpful?

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You posted with a Firefox beta release (81).

Does this also happen with the Firefox 80 release with a new clean profile and with hardware acceleration possibly disabled ?

Helpful?

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Chosen Solution

Hello!

After digging into the CPU usage indepth, it turns out that it wasn't firefox at all... it was malwarebytes!

As soon as I closed MB, bam, firefox works flawlessly again.

Thanks for the help!

Modified by agouranga

Helpful?

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agouranga said

Hello! After digging into the CPU usage indepth, it turns out that it wasn't firefox at all... it was malwarebytes! As soon as I closed MB, bam, firefox works flawlessly again. Thanks for the help!

I'm having the exact same issue, and I don't have Malwarebytes on my computer. Took one further step of uninstalling all anti-malware from my computer, and I'm still having this problem. And the first line in my graphics section is "Basic," if that helps.

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I've been having this problem, and I've done everything the OP has done, and taking the extra step of uninstalling all anti-malware to see if it was causing the issue. Restarted in safe mode, and the issue was still present, just not quite as bad. It's getting stale. And, at least in my case, it's clearly not anti-malware causing the issue.

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