I had this problem too. For me it was some kind of conflict with asghost.exe (works with my fingerprint scanner which I never use). When I terminated this process everything settled down.

Same symptoms. Since updating to version 6, Firefox spikes to 100% CPU every ten minutes or so. It lasts for about twenty seconds.

Same symptoms as well. Have tried starting in safemode, disabling addons etc. as detailed in solutions elsewhere on this site, but the problem remains. Have completely uninstalled and reinstalled Firfox as well, but no good.

The problem happens instantly whenever I open a link in a new tab or have multiple tabs. The high load (95-100%) does not reduce from this point on and the only solution is to kill Firefox. I'm running XP SP3 on AMD 64 platform.

I have the same problem. I could not find a solution yet. Shall I go back to FF 5?

Troubleshooting extensions and themes

• https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes

Clear Cookies & Cache

• https://support.mozilla.com/en-US/kb/Template:clearCookiesCache

Clear the Network Cache

• https://support.mozilla.com/en-US/kb/How%20to%20clear%20the%20cache#w_clear-the-cache

Update All your Firefox Plugins

• https://www-trunk.stage.mozilla.com/en-US/plugincheck/
• http://www.mozilla.com/en-US/plugincheck/
  • Remove Checkmark from Downloading other Optional Softwares with your Plugins (e.g. Toolbars, McAfee, Google Chrome, etc.)

Troubleshooting plugins

• https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins

Check and tell if its working.

I tried this today, and it is working now: Click Firefox > Options > Options > Advanced ... then Uncheck the option "Use hardware acceleration when available"

I tried the above suggestions (clearing cache and cookies, clearing network cache, disabling all plugins and extensions, and disabling hardware acceleration) but it did not help.

I notice firefox goes straight to 100% CPU when I click on the history menu but not on other menus. There seems to be a pattern at other times it enters a 100% CPU phase but I have not figured out the pattern yet.

I am using Mac OS 10.6.8

I really like the tab grouping feature. Well done. Chris

Firefox Consumes a lot of CPU Resources

• https://support.mozilla.com/en-US/kb/Firefox%20consumes%20a%20lot%20of%20CPU%20resources
• http://kb.mozillazine.org/Firefox_CPU_usage

High Memory Usage

• https://support.mozilla.com/en-US/kb/High%20memory%20usage
• http://kb.mozillazine.org/Reducing_memory_usage_-_Firefox

Check and tell if its working.

Sorry none of those suggestions are helpful. I already run a flash blocker and have also tried disabling it, I don't view PDFs within Firefox and surely Firefox should be able to handle any JavaScript on a fresh start with only this very page? Firefox does not hog the RAM when the CPU problem occurs.

Still if I to the history menu Firefox hogs the CPU and becomes unresponsive for up to 2 mins. It is very frustrating and there are only so many times I can test it because the time quickly adds up. I'm actually considering moving over to another browser until this issue is repaired.

Should I bother try to reinstall or are there other configuration files I can delete/reset?

Cheers, Chris

Firefox Hangs opening the History menu or the History sidebar

• https://support.mozilla.com/en-US/kb/Firefox%20hangs#w_hang-opening-the-history-menu-or-the-history-sidebar
• http://kb.mozillazine.org/Firefox_hangs#Hang_using_page_history

Check and tell if its working.

Works! I cleared my browser history (reluctantly) and it does not hang whenever I go to my history menu any more. I'll come back to you if it stills periodically hangs. Thanks for you help and sorry it was not an interesting problem/solution + but I hope other people's solutions are as simple. Cheers.

Tried all of the above and have disabled every extension and plugin, but it is still going to 95-100% CPU load and the memory usage increases at the same time.

@KennyBoy73 Create a New Profile as a test to check if your current profile is causing the problems.

-> Basic Troubleshooting: Make a New Profile

• https://support.mozilla.com/en-US/kb/Basic%20Troubleshooting#w_8-make-a-new-profile

-> If that New Profile works then you can recover your Bookmarks and Passwords from the Old Profile.

-> Recovering important data from an old profile

• https://support.mozilla.com/en-US/kb/Recovering%20important%20data%20from%20an%20old%20profile

Check and tell if its working.

Well, creating a new profile appears to have done the trick this time. I tried that before I posted to this forum, but there was no difference. But FF has been running OK all day today. Thanks for your help mha007