Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

firefox lagging due to high cpu usage

  • 4 replies
  • 1 has this problem
  • 80 views
  • Last reply by agouranga

more options

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 (4)

more options

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

Helpful?

more options

Hi,

Thanks for the reply.

Yes webrender is there in the first row.

Helpful?

more options

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?

more options

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?

Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.