New local AI integration into Firefox spurs complaints of ‘CPU going nuts’ — chip and power spikes plague new version 141.x

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CPU and power spikes appear to come from inference process related to ‘AI-enhanced tab groups.’

Firefox browser
(Image credit: Mozilla)
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Update, August 13, 7am (ET): In a statement, a Firefox spokesperson told Tom's Hardware: "We’re working to improve client-side matching in the address bar, which makes it possible for users to recall previously visited websites without remembering exact keywords in the URL or page title. We unintentionally shipped a performance bug during the phased rollout of this feature, which processes information privately on-device. After receiving reports of issues that hadn't come up in our testing, we reversed the rollout and the performance issues should be resolved. We are working on a fix.”

Firefox rolled out update 141 last month, but there has been an issue simmering under the hood which has only now come to a head. PC enthusiasts don’t like their CPU cycles being wasted, but there is evidence that Firefox v141’s headlining new feature, AI-enhanced tab groups, is chewing through more horsepower than it should. Quell surprise – AI sapping your precious watts for little to no tangible benefit…

Firefox browser

“Now Firefox can help you keep your tabs organized, automatically. A local AI model identifies similar tabs, automatically organizes them into groups, and even suggests group names. Everything happens on your device to respect your privacy.” (Image credit: Mozilla)

The first release of Firefox v141.x was on July 22, but we think that the unsatisfied muttering about AI-enhanced tab groups is only starting to become audible is as this is a feature that is “part of a progressive rollout.” In other words, Mozilla has been quite cautious with switching on this feature to a wider audience.

Leading the throng, who have now found their voices, are the two Reddit threads linked in the intro. IamgRiefeR7 was among the first on the Firefox Subreddit to float the idea that the Mozilla-developed browser was to blame for a recently observed flurry of “rapid CPU and power spikes,” uncharacteristic of the intensity of their browsing activity.

Firefox inference process caught red-handed

Investigations by IamgRiefeR7 pointed to a process called ‘Inference’ fluctuating between 0.05% and an astronomical 130% CPU usage. This was observable in Firefox’s about:processes status page, which you get to by inputting that string into the browser address bar. IamgRiefeR7 tried to kill the process, but such action isn’t recommended, as Firefox subsequently becomes unstable.

Elsewhere, on Reddit (linked top) st8ic88 crafted a very popular Firefox Subreddit thread after noticing “my CPU going nuts for no reason.” This Redditor was clearly exasperated with their laptop CPU overworking, and battery depleting extra fast, all due to some AI process that merely groups tabs.

For those selected for the progressive feature rollout, our only wish is that Mozilla makes this – and future AI shenanigans – easy to toggle on or off. The Firefox browser has a lot of attractive qualities, including its customizability. However, the experience of IamgRiefeR7 – where the browser became unstable when the inference process was killed – isn’t promising.

We took a look at replicating this issue in Firefox 141.x but do not seem to be among the progressive feature rollout chosen. Mozilla says this gradual rollout tactic “helps to get early feedback to catch bugs and improve behavior quickly.” However, the release notes for version 141.0.2 (Aug 5), and 141.0.3 (Aug 7) don’t mention any AI CPU sapping processes bug fix.

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Mark Tyson
Mark Tyson
News Editor

Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.

9 Comments Comment from the forums
  • Alvar "Miles" Udell
    Laughs in Microsoft Edge
    Reply
  • usertests
    I would probably use a feature that automatically grouped tabs together using AI, because I'm so lazy about tabs myself and don't want to fiddle around with groups manually.

    In the meantime, I'm wondering when local LLM support will hit the HTML living standard and web browsers, because I'd like to play around with it without requiring external libraries.
    Reply
  • Aeden
    I thought I finally found the culprit behind Firefox taking upwards of five minutes to restore my tabs. Turns out my computer is just really old and feeling its age.
    Reply
  • hwertz
    I assumed this tab grouping thing was off by default. If not, they should just do that. Problem solved.

    The other thing that inference is used for is translation -- this does burn some CPU cycles but I do prefer local translation over the data shipped off remotely (which is how it worked before.). This in fact works quite well.
    Reply
  • TheBobs
    So -- this is about as easy as you could imagine to turn off

    in 141.0.3 simply open settings, search for "suggest" and untick the "Use AI to suggest tabs and a name for tab groups" (Its under General -> Tabs, right at the top of Settings) Yup, it seems to be on by default in this particular update. Easy enough to change. I get how resource-sapping defaults can be annoying, but sitting here with... quite literally hundreds if not thousands of tabs open, I didn't notice the impact, but do expect to be a 'bit' snappier with the setting off (Win11/GTX GPU + Core i9 with 64GB certainly helps with that).
    Reply
  • WonkoTheSaneUK
    Tech site "The Register" has a comprehensive how-to on completely disabling this flavor of AI.
    Reply
  • 2Be_or_Not2Be
    Really, you don't need AI to suggest names for Tab Groups or even tabs to add into a group. If you want to add AI capability, perhaps you could have it conduct background searches for content related to the tab, and then suggest that new content, if desired.
    Reply
  • Alex/AT
    Actually it may make more sense to do OS-wide configuration option (i.e. registry entry in Windows and some /etc file in Linux) that may state to all applications in the system to 'Disallow any "AI" functions'. As this crap will get integrated more and more. And yeah, make legal policy that user must be able to disable all "AI" functions in all "AI"-integrated applications alongside, so application developers have to conform. The big fat aim is to avoid these major power spikes that may come from millions of machines running "AI" after another software update for nothing. Another big fat aim is to free users that do not want it from any unpredictable "AI" behavior of their systems.
    Reply
  • t3t4
    I've been seeing this problem for a while now, specifically on youtube. As far as I've been able to discern, it's got nothing to do with AI anything but rather 'hardware acceleration'. I don't have anything AI enabled, and I could never be so lazy that I need some useless bot to sort my tabs! That's just another useless bloated feature nobody ever asked for. But my issues on youtube has caused me to spend a lot of time in the FF process manager, and I've seen 100 plus percent cpu usage which makes no sense to me. How can anything be used beyond 100% of it's capacity??? But what I do not see is any correlation to real actual CPU usage in the windows task manager.

    FF process manager tells me 100 some percent CPU usage, but windows task manager say's 23 percent. Clearly there is something there I don't understand, unless one of them are lying to me!

    But when I have issues, it's obvious. Stuttering scroll, sluggish playback, green screen video, slow performance in general. The 2 things I've found to bandaid the problem are clearing the cache and disabling the hardware acceleration. But the source of the problem sure seems to be software not properly talking to hardware.
    Reply