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 have this same problem too, much higher CPU usage, and SLOOOOWWWW, even when my activity monitor shows Safari with more windows/tabs open, and using more memory! Many Google searches or sites simply won't open at all!

I'm on a Mac, so it's not just a Windows issue...

I have this same problem too, much higher CPU usage, and SLOOOOWWWW, even when my activity monitor shows Safari with more windows/tabs open, and using more memory! Many Google searches or sites simply won't open at all!

I'm on a Mac, so it's not just a Windows issue...

Plus, as for Java & Flash, when I clicked the Update link, it told me I urgently must upgrade Flash (although I HAVE the most up-to-date version), and to also update Java, (which I also HAVE the most current one), so where's that leave me???

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 don' t have Java quickstart, & have only a single Java embedding plugin (which the Update function keeps telling me is outdated, which it is not, as the Java website even says that Apple has there own Java, and the one I have is the most up to date. Also, I use FlashBlock, so I don't have flash activity going on anywhere but when & where I want it, yet still FF stalls & hogs memory..

This problem has been a nagging one for quite some time, & the other is (as a consequence) I keep getting error windows about a script halting forward progress, & do I want to stop or continue it's loading. Of course, I click Stop, but it still stalls, with the spinning blue ball! Plus, it pops this message up even when I open an empty tab, or even leave Mail, and just come to an already opened FF page! Very frustrating to say the least...

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