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Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

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Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

Almost spontaneously, Firefox would freeze and become unresponsive. During this time, every Firefox window is whited-out and do not respond to any input, and the Firefox process uses up 100% CPU. All active content running at the time of the freeze, if any, continue to function as normal (Videos continue to play, web applications providing audio notifications send them as normal, although any visuals are now not visible as the browser windows are frozen. The sound continues uninterrupted, however.)

Freezing may occur at any point. Even when the user does not interact with Firefox, it may still freeze. Freezing persists with all addons and plugins disabled.

The freeze would last between a few seconds to a minute, and subsequent to the freeze, Firefox always resumes responding as if nothing had happened. While it does not result in significant losses, the freezing is extremely inconvenient and may occur as frequently as once every ten minutes.

The freezing symptom is universal across all versions of firefox between 5 and 8.0a2.

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1 ACCEPTED SOLUTION

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New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

I've had this problem since I upgraded from FF5 to 6.02. I had the Aurora dev version installed, so I too can confirm the problem occurs in various versions. Exactly as OP mentioned: max CPU load, application freezes, even without any websites open - It once even froze immediately after startup while clearing the browser cache.

My profile has been very old. I too disabled all Addons and Plugins, and the problem persisted. After that I uninstalled Firefox but kept my profile - no luck.

Nevertheless, a complete reinstall plus removal of all profile data (C:\users\me\AppData\Local\Mozilla and C:\users\me\AppData\Roaming\Mozilla - export your bookmarks first of course) solved the problem. Downside is, you need to reinstall all AddOns, and your settings and cookies are gone. But these freezes were even more annoying, so my advice would be to create a new profile.

7 REPLIES
New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

I've had this problem since I upgraded from FF5 to 6.02. I had the Aurora dev version installed, so I too can confirm the problem occurs in various versions. Exactly as OP mentioned: max CPU load, application freezes, even without any websites open - It once even froze immediately after startup while clearing the browser cache.

My profile has been very old. I too disabled all Addons and Plugins, and the problem persisted. After that I uninstalled Firefox but kept my profile - no luck.

Nevertheless, a complete reinstall plus removal of all profile data (C:\users\me\AppData\Local\Mozilla and C:\users\me\AppData\Roaming\Mozilla - export your bookmarks first of course) solved the problem. Downside is, you need to reinstall all AddOns, and your settings and cookies are gone. But these freezes were even more annoying, so my advice would be to create a new profile.

New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

Thank you! I had not assumed that the user profile would be the root cause of this issue. This fix seems to be working thus far; I'll report back again if it does not recur within a few days.

(I did not think this would actually work, so I didn't back up my old profiles; oops. Now I have nothing to compare with when I try to hunt down the problem. Has anyone here managed to narrow down the problem to a specific part of your user profile? It's great to have found a working solution to the issue, but it would be even better if the source of the problem and why it occurs can be tracked down.)

New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

captmcneil's response definitely helps. I don't know why someone marked it as "unhelpful", but if you followed his exact instructions, then it should completely resolve your problem.

New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

There are at least four similar topics here about this problem and I have clicked the button that I too have the problem on each and every one of them.

This is the first time in years that Firefox has given me a serious enough problem to render it unusable.

New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

Nope, sorry that wasn't it.

New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

I found the solution about an hour ago - since then NO MORE FREEZING for the first time in weeks! Install this add on - https://addons.mozilla.org/en-US/firefox/addon/places-maintenance/ Open the dialog with Options. Select Expire on the list, and click on Execute. After spending weeks trying so many possibilities, this took about three minutes. I have run Task Manager resource monitors on CPU, Disk, and Memory since then - clean!

New Contributor

Re: Firefox constantly hangs and freezes; uses 100% CPU during the freeze.

That did not help whatsoever