How To Solve 100% CPU Hogging by Firefox in 2 Steps

By Angsuman Chakraborty, Gaea News Network
Monday, April 30, 2007

I am using a Core 2 Duo E6600 (2.4 GHZ x 2), one of the best processor (review) in market today, with 2GHZ of DDR 2 667 RAM (read about my dream computer setup), and yet Firefox manages to hog 97% of the CPU in no time at all. I admit that I open too many windows but its is still extreme, don’t you think? So I set upon to find a solution to the CPU hogging problem and you will be surprised to know that it is really very simple.

First of all I made Flash optional by using the FlashBlock extension. It is a nice little extension which simply displays a play button instead of Flash ads. If you wish, you can play the Flash content by clicking on the play button. In the past I have faced Firefox slowdown issues in Windows which were related to too many Flash content being displayed. However it didn’t help this time.

I then disabled Java. In Preferences->Content menu uncheck Enable Java checkbox. That’s it.
I restarted Firefox. I still have same number of windows (30+) as before and with same content and yet Firefox CPU usage became negligible! I have solved the problem.

To summarize the steps to reclaim your CPU from Firefox:
1. Install FlashBlock plugin
2. Disable Java

Update: I found that even with low CPU utilization Firefox was still hanging. The solution was to disable SearchStatus extension.

December 19, 2010: 7:12 pm

Sometimes FireFox crashes. I don’t know why this happens and I meant it “constantly” I am so confused about it. Can you guys help me out?

November 25, 2010: 11:54 pm

I was looking for some ways to get me better updated on firefox browser. But for some reasons I quit using firefox for it constantly crash. I use Google Chrome and am very much satisfied with it.

November 3, 2010: 4:19 pm

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October 22, 2010: 2:23 pm

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September 28, 2010: 3:26 pm

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August 20, 2010: 11:43 am

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August 17, 2010: 4:02 pm

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August 12, 2010: 3:52 pm

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August 7, 2010: 2:07 am

It is a nice little extension which simply displays a play button instead of Flash ads. If you wish, you can play the Flash content by clicking on the play button.

August 6, 2010: 8:24 pm

Thank you very much for posting a lot of this excellent info! I am looking forward to seeintg more posts.

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June 23, 2010: 6:42 am

I used to have Firefox hogging the CPU within a few hours after starting it, however I soon realized the culprit is Facebook. Apparently the JavaScript on Facebook hogs Firefox for some reason.

I resolved this by blocking scripts on Facebook, which unfortunately makes the site unusable, so I now use Chrome or IE to access it, and keep using Firefox for the rest of the sites.

I can have literally hundreds of open tabs on Firefox with only 3% CPU usage at most, as long as no Facebook Java scripts are running.

June 12, 2010: 4:38 pm

Well I’m running Windows 7 64-bit with 4GB of RAM on a dual core Pentium and Firefox is still crap on this. It’s okay until I leave the PC to do something else and let it go to sleep. After I wake it up it’s a 50% hog. It’s worse than Internet Explorer!

The developers are hopeless and lazy about dealing with this and I’m close to giving up on it and trying something else. Opera used to be good but now it’s just been wrecked by the geeks and not as straightforward as it used to be, Avant looks like IE in a different disguise, Chrome is okay but it doesn’t save tabs. So… I don’t know.

May 20, 2010: 12:39 am

I experienced the same problem on an E6800, 4gb DDR2 mem, Xubuntu 10.4. I tried out the google Touchgraph java applet; after closing it, and for about 5 minutes until I figured out that’s what it was, firefox+java absolutely hammered both cores. The solution was just to kill Firefox. Now with Chrome supporting extensions, it’s starting to become feasible to just use something else, such as Chrome, over Firefox.

Anyway, java was definitely the culprit for me.

May 11, 2010: 10:07 am

thanks for the tips, I would also like to add that disabling AVG addons descreased Firefox’s CPU usage dramatically! Fireforx went from 44% CPU usage to 0~1%!

April 27, 2010: 10:04 pm

THANK…YOU…. this was pissin me off, simple solution. Works perfect.

April 19, 2010: 11:58 am

Flashblock requires java to work, right?
So doesn’t step 2 wipe out step 1?

April 3, 2010: 9:50 pm

many thanks for your post. this has been getting at me for a few weeks now.

March 18, 2010: 10:31 am

Another way is to uninstall the crappy thing.

March 16, 2010: 10:08 pm

I had same problems with CPU running at 100% with or without internet.
Fan keep CPU cool was plugged. Open up computer (while power was off) and cleaned out build up of dusk all over the fins of cooling fan covering CPU. Now CPU is running from 3-20 %. May go up to 100% just for one second.

Sprightly jarmis
March 16, 2010: 5:35 pm

I think some of you people need to get out more. The guy is just offering a suggestion that worked for him, stop complaining if you don’t want to use it - don’t.
Ultimately there is so much guesswork with FF (much as I love it and use it on all machines and OS’s) is because there are so many incremental changes that render toolbars, add-ons and extensions incompatible or troublesome. Its difficult to tell what the underlying problem is because it might not be same on version x.x.x.x.1 as it is on version x.x.x.x.2.1. The Mozilla guys are superstars but they have proved their point, now please release fewer and more stable properly tested versions guys.

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January 30, 2010: 9:47 pm

Lol - so your solution to flash players hogging the CPU is to *not* view flash video? That’s hardly a solution.

January 22, 2010: 5:04 am

Switch to Chromium: Using the same version of flash (10.0r42) in both Firefox and Chromium in Ubuntu, Chromium outperforms Firefox on all flash sites I have tested. And not just by a small margin. I have a lowly AthlonXP 2400+ and Firefox uses 100% on all flash enabled sites whereas Chromium has a brief burst of high CPU use then it goes back to normal - this makes all sites usable again for me.

November 14, 2009: 11:31 pm

None of these solutions work. Aren’t we all tired of guesses from people who think they know everything about computers? Everytime we have a computer issue we have to wade through a thousand different sites with guesses from self proclaimed computer experts. If you haven’t personally duplicated and fixed this exact problem on several machines than shut up. We don’t want to waste our time trying a million things hoping one will work. Only offer a solution if you are sure it will work. We don’t care if you say “Well this works for me!”. Obviously you have a different problem than the rest of us because this issue is still happening. Your advice didn’t help. The Intertubes are littered with this kind of pseudo-computer-guesswork and we are all tired of reading it all and wasting our time. Flash still uses 100% CPU cycles after all of these guesses were tried.

October 14, 2009: 10:08 pm

better solution is deleting any file starting by the name firefox in c:/windows/prefetch

it reduces your FF usage by 20-30%…

October 14, 2009: 10:04 pm

this is not realy a soluction… disabling flash? desabling javascript? why not just start browse in text mode?

October 10, 2009: 8:32 pm

I am getting the same exact problem with version 3.5.3. and I thought Firefox was going to take care of it!

October 9, 2009: 1:05 pm

how to fix firefox 100% CPU usage / flash player

enable Flash hardware acceleration

1.type about:config in firefox browser.cache.memory
3. change it from true to false
4. restart firefox.

take care


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