I just tested it and it was quick. If you close Firefox, then start Firefox in Safe Mode, does the problem still occur? To start in Safe Mode, go to Help > Restart with Add-ons Disabled.

If the problem does not occur in Safe Mode, then you can disable your extensions one-by-one until you find out which one is causing the problem. For more info, visit Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

You should also consider updating your version of Firefox. If you don't know how to do that, there are instructions at Update Firefox to the latest release.

Well, how did you test it? How much did you delete? Did you monitor your CPU activity? You're basically giving me fluff.

I tried again with Add-ons disabled, same thing. The troubleshooting pages are useless for this issue, or I wouldn't have posted a question. I'm not going to update this installation of Firefox, but I had the same problem in the latest version as well.

Mozilla has never released a Windows 64-bit version of Firefox, for a reason.

Try PaleMoon support, after all you're using their browser. http://forum.palemoon.org/

Awesome snark, moderator-bro. You missed "I'm not going to update this installation of Firefox, but I had the same problem in the latest version as well." This is a consistent problem with all Firefox versions.

No, Ed is right. I just missed the fact that you're not using Firefox, because it says "Firefox 24.0" under System details. For Pale Moon stuff, it really does belong on their site, because there are quite a few differences between the two, and they would be better equipped to help you.

Having said that, when you say you had the same problem with the latest version, which version is that?

Firefox 29, with the GUI overhaul. It had the exact same problem.

randomanon1234,

You posted here with PaleMoon in the Firefox support forum, and didn't specifically refer to which version of Firefox your problem is/was with. We assume that the support question is about the browser used to post here, unless that is obviously incorrect; like the thread was started on a Mobile device, or using IE or Chrome - then we ask, if the Firefox version wasn't stated along with the question.

You might think PaleMoon and Firefox are the same and that I am "splitting hairs", but "we" have had a discussion with and initiated by MoonChild of the PaleMoon project in the Contributors area over "us" referring to PaleMoon as a "3rd Party build" of Firefox. He insists that PaleMoon is a Gecko "fork", not a re-branded version of Firefox - IOW, a completely separate browser that uses much of the same code that is in Firefox. MoonChild also informed us that the PaleMoon project had their own support forum, and asked that we refer "his" users that come here, over to the PaleMoon project forum for support.

Now, if that constitutes my being "snarky", I apologize. If you are talking about problems with a version of Firefox that you used to use, you may provide feedback to Mozilla here - https://input.mozilla.org/en-US/feedback

If you aren't using Firefox now because of that problem, this conversation isn't a "support topic".

I moved to PaleMoon due to the UI overhaul. When I found it satisfactory, I attempted to delete all of my browsing history in Firefox 29. The program froze up and took up an entire core for over five minutes before I ended the task and simply uninstalled it.

It was a problem with Firefox 28, 27, and so on. I have a huge browsing history, so I can't test it on a fresh install of Firefox, as the amount of sites in my history may be a factor.

I have a feeling that none of you have an answer or a solution, no matter the Firefox version.

"Firefox 29, with the GUI overhaul. It had the exact same problem."

Looking at the list of bug fixes for 29.0.1, I don't see anything that might be related to your issue. I don't recall this being an issue with previous releases as well. Right now, I'm betting that the issue is local to your profile.

Try deleting the your history file.

1. Go to Help > Troubleshooting Information, then click on Open Containing Folder. That will open Windows Explorer in your Firefox profile.
2. Close Firefox.
3. In your profile folder, delete the file places.sqlite (or rename it). The next time you open Firefox, a new places.sqlite will be automatically created.
4. That file contains both your history and bookmarks, so you'll need to restore your bookmarks. For instructions, visit https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them#w_restoring-from-backups

Alright, thanks. And if I've been overbearing, you have my apologies. I went ahead and renamed places.sqlite, and palemoon even managed to automatically restore my bookmarks.

Just for fun, I went and copied the old places.sqlite into my fresh new Firefox 29 install, and tried to Forget About twitter.com. See attached pic: 25% CPU usage and it hung. When I went ahead and ended the task, and reopened it, it was still hanging.

So: same old news. Y'all have a problem. You say it'll get noticed if I submit something here? https://input.mozilla.org/en-US/feedback Or will it get ignored?

I don't want to underestimate your problem, but 138 M isn't a lot for the firefox.exe process. I see almost 300 M after launch with using the default homepage, with the large number of extensions that I have installed (over 55 / with 6 more disabled); and I only have 2GB of RAM on-board (32-bit WinXP and 2.2 GHz AMD64-AM3 socket processor) and have no problems running two Firefox Profiles simultaneously. But I rarely delete history, so I'm not striking a direct comparison to your described problem.

How much RAM do you have?

I said nothing about RAM. Firefox has RAM issues, but I have 12GB of the stuff, and it doesn't bother me unless Flash gets out of hand. I can comfortably afford to give 2GB of RAM to Firefox, though other problems arise by that point. (Palemoon, btw, is much more responsible about RAM allocation.)

I was highlighting the CPU usage there: that's 25% of my CPU, or an entire core, eaten up by Firefox when it hangs because I tried to delete the history. That's Firefox 29, though I could illustrate the same in previous versions, or forks like Palemoon.

"Just for fun, I went and copied the old places.sqlite into my fresh new Firefox 29 install, and tried to Forget About twitter.com. See attached pic: 25% CPU usage and it hung. When I went ahead and ended the task, and reopened it, it was still hanging. "

I'm not sure I understand. I told you that places.sqlite might be the cause, and to let Firefox create a new one. Above, you say you tested with the old places.sqlite. :?

If removing places.sqlite doesn't fix it, it might be a cookie issue. "Forget about this site" not only removes browsing history, but download history, cookies, cache, active logins, passwords, saved form data, and exceptions for cookies, images, pop-ups for that site. In that case, try resetting your Firefox profile. For instructions, visit Reset Firefox preferences to troubleshoot and fix problems

Removing places.sqlite fixed Palemoon. So to test it on Firefox 29 (so it's relevant for you), I copied my old places.sqlite back to Firefox 29. It's a problem in Palemoon and Firefox 29.