Join the Mozilla’s Test Days event from Dec 2–8 to test the new Firefox address bar on Firefox Beta 134 and get a chance to win Mozilla swag vouchers! 🎁

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

FF is using only 4 of the 8 cores in my CPU. Why isn't it using all 8?

  • 5 replies
  • 3 have this problem
  • 4 views
  • Last reply by Burgomatic

more options

Task Manager shows that even when opening 15 pages in tabs, FF is still only using 4 out of the 8 cores in the CPU. Is FF made to utilize only 4-core CPUs?

Task Manager shows that even when opening 15 pages in tabs, FF is still only using 4 out of the 8 cores in the CPU. Is FF made to utilize only 4-core CPUs?

All Replies (5)

more options

Firefox does not need to use 8 cores. 4 cores is plenty for it. Even games don't need 8 cores. Max, games would need is 4 cores.

Modified by Microrobot

more options

Firefox is 32 bit if you want to use all 8 cores you can use a 64 bit variant of firefox such as

NOTE: Both of these versions of firefox are unstable and may combust.

Modified by kobe

more options

Maybe because Firefox is a 32-bit application on a 64-bit operating system? Just a WAG.

more options

There is no need for Firefox to be using all your cores, that would just be a waste of resources and energy.

more options

I agree that there's no need to use all cores, but I thought modern apps were made to use all available power. I didn't know that this was caused by FF being a 32-bit app.

Thank you all for your answers.