Arch Linux

auoax

Member

Registered: 2025-03-18

Posts: 6

Firefox hogging my CPU for no reason (random high CPU usage)

I have recently (1-2 weeks) begun experiencing this weird problem of Firefox heavily using CPU, seemingly for no reason and at random times, while browsing. It's not related to whatever JavaScript the site I am visiting is running, which would be the obvious cause. When I open Firefox's Task Manager, the weird CPU usage stops. I am using the default firefox package from normal Arch Linux repositories. It is possible that the root cause has existed in Firefox for longer than the roughly 2 weeks but I just started experiencing it after I upgraded to the latest version. In any case, this is a relatively new thing.

I cannot pinpoint what exactly is hogging the CPU. I even considered the possibility of it being some kind of malware hiding inside the Firefox process surreptitiously mining cryptocurrency or something which would be really unusual on Linux but I guess the recent AUR malware debacle (and the xz backdoor case) has made me paranoid. However, it seems that others are experiencing this exact same issue as well: https://www.reddit.com/r/firefox/commen … s_soon_as/

I would really like to continue using Firefox and avoid contributing to monopoly of Google Chrome/Chromium-based browsers but this is slowly but surely driving me insane. The CPU usage is significant enough to ramp up my temperature controlled case fans. When I use other browsers, like Chromium, this issue does not happen.

Have any of you experienced this same problem? Do you know if anybody has been able to trace this issue back to some exact feature within Firefox? I have AMD Zen 5 CPU and Nvidia graphics if it could be hardware related. I tried to disable all AI related functionality in Firefox preferences and deleted all my extensions other than uBlock but to no avail.

SimonJ

Member

From: Spain

Registered: 2021-05-11

Posts: 387

Website

Re: Firefox hogging my CPU for no reason (random high CPU usage)

This is not helping directly but if you are disabling much of what FF comes with maybe try Librewolf, I switched and it does what I need without all the cruft I don't. It is in the repos now so managed by pacman also.

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Rlu: 222126

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 78,103

Re: Firefox hogging my CPU for no reason (random high CPU usage)

I assume opening about:processes implies moving away from the tab where that happened?

https://wiki.archlinux.org/title/Firefo … leshooting
Does it happen in --safe-mode?
Some extension?
Does HW acceleration work?

Does it happen on bss.archlinux.org?
Does it happen when you completely disable JS?

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