You can try to disable the Java Quick starter extension and remove all Java Console extensions.

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

See also:

• http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions
• http://www.java.com/en/download/help/quickstarter.xml

Thank you,

I removed 8 older versions of Java console this reduced the memory used from over 500MB down to a more acceptable 150MB ish disabling Java quick start fixed the problem completely and reduced memory usage further to 67MB and bringing cpu usage right down to low levels .

) :) :)

You're welcome

I've been experiencing this cpu hog situation of firefox for quite some time. It appears to be related to sites which utilize flash. Because until a site is loaded which contains flash, there is no cpu issue. But once the site is loaded (and I've found this to be true with every site containing flash), the cpu usage jumps to roughly 100%. Even after the site is closed (by closing the tab or even the window) as long as firefox remains running the cpu usage will not drop below 100% again.

Many have said this is an adobe flash issue. Others have said it is a firefox issue. What I do know is that I have both the latest firefox and latest adobe flash player and it happens. When I use IE, the cpu usage even with multiple flash sites open never goes above 25% and once the site which contains the flash is closed IE cpu usage drops down to almost nothing. I really prefer the flexibility of firefox with respect to addons, but until this cpu usage issue with flash and firefox is resolved in some fashion, I have no option but to go back to IE as a browser.

My problem was as remedied above, by removing Java Quickstart and excess Java consul extensions.

I have never trusted flash, I use prefbar http://prefbar.tuxfamily.org/ which has a simple flash enable/disable check box and (although I have never needed to use it) a Kill Flash button. It also enables the on the fly changing of many other settings

I got to the point that Firefox 3.6.11 and 3.6.12 and beta 4.07b ground my PC to a halt for two days with 100% CPU usage and 400+ MB of memory usage. I tried all the suggestions of turning off Flash and Adobe and Java--even turned off my antivirus, but nothing helped. Then I found the cure. I realized the one thing in common between all these versions was my profile.

First, I backed up my bookmarks. I also made print screen backup copies of my site passwords. Next, I uninstalled Firefox but allowed it to keep my profile (i.e., do not check the box that offers to remove your settings). I went into my documents and settings folder, then applications, then Mozilla, then Firefox, then Profiles. I found the profile with extension "default" and added an extension of ".old" to it.

Then I downloaded a fresh copy of Firefox, allowed it to create a new profile. I made a backup copy of the new profile.

Then I followed the directions on this page:

http://support.mozilla.com/en-US/kb/Recovering+important+data+from+an+old+profile

to retrieve my passwords and form history. You can also retrieve your bookmarks, but since I backed up my bookmarks before uninstalling Firefox, I "restored" my bookmark backup through the bookmarks menu. I copied each of the folders necessary for passwords and form history into the newly installed Firefox profile.

Then, total joy. Firefox and I are friends again. I have all my plug-ins/extensions running, am using tabbed browsing, leave Firefox open, and no more CPU hog!

Hope this helps!

What strikes me with this post is that the original problem was on Windows XP and solved the entire continuation is with boxes running Mac OSX! (a so called superior variant of BSD)

The solution I proposed is in Windows XP. I had tried the earlier proposed solution on my Windows XP system, and it did not work for me. I wanted to make an alternate available for those whose systems might have similar CPU usage problems.

as soon s the 3.6.12 update came, my shiny new PC (XP) with lots of power slowed right down. With one FFox window open, it zooms up to 500K memory too and can do nothing to fix it. Have fiddled with Java and flash extensions and settings. Freezes the whole machine. Doing FFox Safemode and turning off all extensions/addons doesn't help a bit.

Ending up again just like last year after an update. Were the improvements coming with 3.6.12 worth the memory problem? No. I am going to use Opera................... So much time spent last year and now on this problem trying to fix it on my machine. :(

Hi GolferGuy1, Sorry for the problem you are having, but if you will look at the post I made above, you will see I had the same issues as you. When I took the steps I outlined above, I solved the problem. I am running FFox with less than 10% CPU now and normal memory usage--using Java, Flash, Adobe, and Norton AV. Actually, I tried Opera myself due to the FFox issues, but Opera kept crashing with the flash on Yahoo mail page, so I went back to figure out how to fix FFox. I was just as frustrated as you seem to be until I figured out it is a corrupt profile. Why not give my solution a "shot" golferguy1 before you knock it?  : )

Yes -- I am having all of these problems too. I have Mac OS X 10.4.11

> corrupt profile

It seems like the issue could compound itself when users are ending the process because Firefox is hung. Seems like Firefox should provide a tool to detect and repair problems with profile corruption.

I would also suggest turning Firefox in safe mode. If the CPU is behaving okay at this point, this may point to an add-on. Run Firefox in normal mode, then disable all the add-ons. Enable only half the add-ons and observe. If the CPU percentage is high, then this may point to an add-on you enabled. Disable half of those add-ons and observe. Keep doing this and hopefully you can pinpoint an add-on. Sometimes it may be two add-ons like AdBlock and Flashblock that could be causing a synergistic issue. In those cases, that's harder t troubleshoot. I'm not saying AdBlock and Flashblock are the culprits, I'm just using them as examples to illustrate a point.

For what it's worth, I have tried all the fixes.

I have experimented a bit, shutting Firefox down and bringing it back up while watching the CPU usage via the Task Manager. What seems to happen is that it starts out as you might expect when initializing itself (60 or 70%) and then just sort of ramps up to and average of 94-95%. And, this is when nothing is going on, other than the "Start Page". When I am actually using it, it obviously slows itself down a lot.

It would be kind of nice to have this fixed, since I have no great love for IE.

I have been experiencing the crashes and excessive CPU usage on both my desktop and netbook, which are running the most current version of Firefox. My laptop, which I never updated to the latest version of Firefox is working fine. Today, as I was searching for a solution, Firefox crashed while on the Mozilla website.

thank you for the great advise. do you know if this will also work on windows 2000? every time i start a game ( farmville, cafeworld, cityville) i also freeze up. i can do many others that do not have alot of activity on it like mafia wars and game channel. any help would be appreciated.

i have windows 2000 5.00.2195 service pack 4

260,656 kb ram  
yes i know this is very outdated but until the other computer is fixed i am stuck with this one.

This was meant for jcbeliever

Hi footballma32, have you tried the games in Internet Explorer? Does the same "freeze" happen there? What you are describing sounds more of a problem with a 3rd party program like "Flash" or "DirectX" that are often used with games. I would also check to see if you have the latest graphics (video) driver that your system can use. You do not have much RAM available, but Windows 2000 does use less. That can also cause a slow up. Try to close any other unnecessary programs when playing these games. I hope this helps!

I've always been a fan and proponent of Firefox until first the start-up got so slow -- and then it started hogging i00% of my CPU between the firefox running program and the firefox plug-in container. Firefox has been pushing for people to try their newest product, Firefox for Android, but there is no way I am going to load Firefox on my Samsung Epic Galaxy 4G mobile phone so that it can lock that up too! In the meanwhile, I have to keep copies of IE8 and Chrome on my PC to use as backups when Firefox freezes my computer playing a facebook game like Family Feud. I reboot and use IE for a while. I hate this, I used to love FF.

I originally asked which version of Firefox is the last stable version for older PCs as I was considering updating. Now I will NOT!! I was having CPU pressure problems with upgrades a way last year and did some research back then to find out that the last stable, non-crash version for older machines was and apparently still is - Firefox Version 3.0.19 - believe it or not.

However, with this version Firefox is at pains to broadcast that this version is no longer "safe". But if Firefox is only going to write software for i-5 dual cores and above computers then those with average and way below average machines are going to have to use OLDER versions of Firefox along with other less RAM hungry 'protection' software.

Currently My line-up is :

Firefox Version 3.0.19 (Old but NO bother, like a charm and add-ons :)

PC Tools Anti-virus (free & not the Spyware doc version) THE lowest RAM on the net (believe me I have tested them ALL!)

Advance System Care Professional (on) and NO trouble. The PRO is what you want.

IOBit Security 360 (on) and NO trouble (Free version is just fine, although I have Pro).

And if you are really F***ed - RAM Booster Free II (Again a sweet one, no trouble at all.)

And my system - a Dell Pentium 4

Now you have an answer. The very BEST of luck!

Crikey