I'm running into firefox hogging the cpu (like 178% in top) sometimes from startup, with 1 or 2 stationery displayed tabs. I'm using firefox-42.0 installed with Ruario's script.I had it also in firefox-32.0.3. Kill it, and it starts again in a few minutes. Or it might not.

I have a standard 14.1 and use AdBlockPlus, NoScriot, and a fkesh video downloader extensions. What's the deal?

It's an issue that seems to affect firefox regardless of the OS. Perhaps cpulimit might be able to help you.

http://slackbuilds.org/repository/14...earch=cpulimit

You'll have to make some changes to how you fire up firefox for this to work.

I never see Firefox CPU spiking except when initially loading a page or watching a video. You may want to try uBlock Origin and uMatrix as replacements for AdBlockPlus and NoScript, they should be a little lighter on resources. I'm not familiar with flash(?) video downloader but you may want to disable that add-on to see if it might be the culprit. Also is the CPU spiking occurring only when you have specific web pages loaded in a tab?

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Unfortunately I have. Both in Windows XP and Linux. I just switched over to kernel 4.1.13 from kernel 4.0.4 and I have just noticed that IceCat, a GNU rebranded Firefox, is not hogging the processor amymore. Hmm interesting. Under kernel 4.0.4 it was running at around 99 percent on both cores.

I habitually have to kill F/F - even on 4.? kernels. Now that you mention it, I haven't really noticed the problem on 4.4.0 though ... hmmm I'll keep an eye on it.

I run a pretty light desktop (just bare Openbox) with the nouveau drivers and haven't seen Firefox have any issues like that in at least a few years (although I've heard others have). My hardware isn't particularly great (first gen i3 and 4GB ram) and I'm also running the newest 4.1.x kernel on Slackware 14.1. I wonder if it's a particular combination of GUI desktop/video driver/hardware/etc. that's causing the CPU utilization issue?

Many years ago, I had Firefox hogging the CPU. Turns out that it was because the spinny thing (when waiting for a page to load) and the graphics driver. Anything animated (like the spinny thing) would do it. Eventually fixed it by using the driver for my card instead of the fallback vesa driver. Obviously I am unsure if that is the cause of your problem.

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Have you tried with a new profile to see if it's due to some configuration issue with yours?

Also, you may want to look at ublock origin instead of ABP. It is supposed to be much easier on your system resources.

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Thank you for the helpful replies, gentlemen

• No, I have not tried with a new profile, but will certainly try it because that box is old and it doesn't hurt.
• I will certainly try uBlock - thank you.
• Yes, eye candy of any sort would slow things. If I'm playing a movie full screen, the thing sometimes can't keep lip movements in synch when someone is speaking fast.Bad built in video.

Well, removing ~/.mozilla did make a significant difference. It still loads a single uncomplicated page http://apod.nasa.gov/apod/astropix.html, displays it, and is still hogging 80 in top, although it goes down to 2%.

Now off to work on sounds and eye candy in about:config. I have to be diligent with that piece of trailing edge technology to get performance. I will also drop ABP for uBlock. I backed up the bookmarks, and can add them in.

That phrase makes me smile.

A low-cpu way of blocking some advertisements is to use the /etc/hosts file to block domains.

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Ingenious! What's the syntax?

man hosts describes the syntax. You can resolve that domains to 127.0.0.0 instead of their IPs, for ex.
As result:

If you want a pre-configured hosts file, winhelp2002.mvps.org contains a massive one with over 15k entries.

http://winhelp2002.mvps.org/hosts.txt

If you want to set up a cron job to update the file automatically, see this page.

It seems to me that anyone who downloads a file as root, replaces /etc/hosts with it, and marks it executable is just asking for trouble.

What if that file was replaced with something malicious? Call me paranoid, but having a script blindly download anything as root seems dangerous. If you plan to do so at the very least add into your download script the ability to verify the file is not malicious. I think it might be safer to set up a squid service that does the ad blocking. A Raspberry Pi or similar micro chip computer would be perfect for such a thing.