Author Topic: Is it normal for firefox to have super high cpu utilization?  (Read 645 times)

Dan Eicher

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Is it normal for firefox to have super high cpu utilization?
« on: August 08, 2025, 11:33:41 pm »
Both in a virtual container and real hardware AOS 5.1.1

Boot, about 3-5% CPU utilization.

Start IBM works 5-8% utilization.

Start Firefox, 89%+ Utilization.

Is that normal expected behavior?

Pete

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #1 on: August 08, 2025, 11:40:06 pm »
Hi Dan

Based on my experience with Seamonkey I would expect around 70% peak during app startup and then low use unless a webpage has a lot of javascript in which case cpus can peak high continuously.


Regards

Pete



Dave Yeo

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #2 on: August 09, 2025, 12:09:23 am »
No. Some scripts will mean high CPU. I advise installing no script. There's also a bug where some GIF's will produce high CPU

Dan Eicher

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #3 on: August 09, 2025, 01:22:03 am »
No add-ins. Firefox directly from AOS 5.1.1 install.

Dave Yeo

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #4 on: August 09, 2025, 01:36:04 am »
How about if you go to about:blank. Type it in the address bar

Dan Eicher

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #5 on: August 09, 2025, 02:48:24 am »
Firefox 45.9.0

Switching to that tab bring cpu utilization down to nothing.

It might be a Dan created problem, the web page I usually open just to test if I can connect to the internet is ibm.com (short url).
BUT, that tab seems to spike utilization.

Now, I need to dig in to performance monitoring.

Dave Yeo

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #6 on: August 09, 2025, 03:30:01 am »
Look at the error console. I'm currently away from my desktop, IIRC, under tools. It's likely some script spinning away trying to do something unsupported by our ancient browser

Eugene Gorbunoff

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #7 on: August 09, 2025, 10:36:22 am »
Start Firefox, 89%+ Utilization.

Current version of Firefox is unusable.
you can't use Bank web-sites, GMail, ..  News sites with never-ending stream of news.
Firefox goes crazy and hangs.

Dariusz Piatkowski

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #8 on: August 10, 2025, 07:34:18 pm »
Start Firefox, 89%+ Utilization.

Current version of Firefox is unusable.
you can't use Bank web-sites, GMail, ..  News sites with never-ending stream of news.
Firefox goes crazy and hangs.

Excuse me????!!!!

Now now...GMail user here for years now...and running quite fine.

....but...as Dave mentioned, you need to prep for this: NoScript helps (but has it's own downsides), uBlock helps as well.

So what specifically do you have problems with re: gmail access?

To the OP (Dan):
There are some things our FF sturggles with, and as Dave already mentioned, some of them can literally peg your CPU to 100% (jscript is perfect example of one such 'bad actor'). I find that a SMP box can actually mange this well and in cases when this does happen there are plenty of remaining CPU cycles to carry on happily.

Keep in mind, I base this on my experience with a 6-core AMD Phenom II X6 CPU and my current AMD FX8370 which is a 8-core CPU. Even though the FX8370 is actually a weaker of the two CPUs, the two additional cores more than make up for what used to bring my PhenomII down completely.

So there are some FF profile settings which will enable you to deal with some of this.

Take a look at:
- content.interrupt.parsing
- content.max.tokenizing.time
- content.maxtextrun
- content.notify.backoffcount
- content.notify.interval
- content.notify.ontimer
- content.siwtch.threshold

All of the above control how FF responds to the updates and the frequency of rendering these updates to the screen.

Beyond these, you have the whole 'network.http.*' bucket which will control your keep-alive stuff, the connections-per-server, pipelining, etc., which when set accordingly to how you connect to the Internet can make a difference.

For what it's worth: if someone can tell me how to extract my settings I'm happy to u/l them here for further review. I think I can just get the flat text from one of the profile files too...let me know!

Eugene Gorbunoff

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #9 on: August 10, 2025, 08:49:06 pm »
To Dariusz Piatkowski

This advice, this information is new for me. Firefox was released in 2018, today 2025.
Why this information was not distributed among OS/2 users?
We suffer all this time.. during the last 8 years.

Dave Yeo

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #10 on: August 10, 2025, 09:14:54 pm »
Dariusz, I'm away right now. You should be able to go to about:support and see the preferences you have changed and I think export then.
Eugene, many of these tricks, no script, ublock_origin and such have been talked about for years. Along with changing user agent, turning off CSS and such. They have become less helpful as our browser simply doesn't support so much stuff. I still do quite a bit with SM, which is basically the same as FF for rendering. But yes, less and less works

Dariusz Piatkowski

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #11 on: August 11, 2025, 04:00:52 am »
Hey Eugene!

...This advice, this information is new for me. Firefox was released in 2018, today 2025.
Why this information was not distributed among OS/2 users?
We suffer all this time.. during the last 8 years.

Well, I would say this information has been out there in one form or another for quite some time now. Heck, I'm sure a lot of it can be found on this very forum...but I will agree with you, we always lacked a uniform "one source of recommendations" that would touch on all of these.

For me it's been a story of changing things little-by-little, testing over a few days (sometimes), and either keeping the profile settings, or reverting back to default.

Dave's hint is good but unfortunately the "about:support" does not provide the full listing that "about:config" does...so instead I've pulled the stuff from prefs.js file and removed the private stuff.

Given how old our FF is, it is becoming difficult to even find the correct Mozilla Dev references to all of these preferences...still, worth a shot.

-Dariusz

Dan Eicher

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Re: Is it normal for firefox to have super high cpu utilization?
« Reply #12 on: August 11, 2025, 11:49:56 am »
Thanks, I will give these a look!