topic High CPU Usage in Mozilla Firefox After Recent Update in Discussions

High CPU Usage in Mozilla Firefox After Recent Update

calce — Sun, 23 Mar 2025 21:37:50 GMT

Hey Firefox community,

After updating to Firefox 124.0 on Windows 11, I’ve noticed high CPU usage, even with just a few tabs open. My laptop fan runs constantly, and performance slows down, especially when watching YouTube or using other media-heavy websites.

What I've Tried:

Disabled extensions & ran in Safe Mode – no change
Cleared cache & cookies – still high CPU usage
Checked for malware – system is clean
Tried a fresh Firefox profile – issue persists

Is anyone else experiencing this? Any suggestions or fixes would be greatly appreciated!

System Info:
Windows 11 (Latest Updates)
Firefox 124.0

Thanks in advance!

Re: High CPU Usage in Mozilla Firefox After Recent Update

rotodisc — Thu, 01 May 2025 17:31:02 GMT

I have. It sucks. And I don't know what to do. No one has any answers.

Re: High CPU Usage in Mozilla Firefox After Recent Update

hirig888 — Thu, 03 Jul 2025 11:21:09 GMT

Same issue, ryzen 7600X , 1080p videos on YT constant 10% +- a few, but never drops, after i reset the whole browser, reopen everything , after that it is normal, WHY? This is wrong, you lot mine my PC? ffs

Re: High CPU Usage in Mozilla Firefox After Recent Update

13thHouR — Tue, 28 Oct 2025 18:54:30 GMT

This is an ongoing issue on Ryzen systems in windows 11.

Firefox (even on a clean install) with the profile created on another drive. Will not let go when you shut it down.

It sits reporting 6% CPU usage on Firefox.exe, the reality it that it is pushing the CPU really hard, and you will hear the fans running, until your system thermal throttles and shuts down.
I have no idea why this is happening, but the commonality seems to be Win 11 and Ryzen CPU's.

Re: High CPU Usage in Mozilla Firefox After Recent Update

13thHouR — Tue, 28 Oct 2025 18:59:31 GMT

On another note, the moment I enter the task manager and stop the Firefox.exe manually, the actual CPU usage drops (not the 6% reported in task manager) and the CPU fan returns to normal.

Mozilla needs to sort this issue as it is going to cause serious damage to Ryzen CPU's.

Re: High CPU Usage in Mozilla Firefox After Recent Update

13thHouR — Sat, 01 Nov 2025 12:51:15 GMT

I just checked this with other rival Mozilla builds like Waterfox. The same issue occurs, whilst it appears to be a Windows 11 issue with Ryzen CPU's Mozilla applications appear to be the only thing affected by it