Some time ago, I installed a Firefox add-on that allows Ctrl-Tab to jump between tabs more intelligently. It remembers the most recent tabs and switches back and forth in that order. It will even display a list of previews (much like Windows Alt-Tab) of the tabs. This was back in the FF3.6 days or so.

When Firefox 4 came out, the add-on disappeared from my list of add-ons, possibly due to some conflict. However, the functionality is still there. It works exactly as it did before.

The problem is that I have strong suspicions that this add-on leaks memory like a sieve. My other computer with Firefox uses much less memory, while the computer with the phantom add-on can get to 1GB+ of memory usage if it isn't regularly restarted.

How do I remove an add-on that is not in the add-on list? And how can I do this safely? I don't want to break my FF install, nor do I want to have to reinstall everything.


Are you sure the Ctrl+Tab functionality actually comes from the extension and hasn't become part of Firefox itself? Because when I Ctrl+Tab through my open tabs, I see exactly the behavior you describe without ever having had the Ctrl+Tab extension.

However, if the problem actually was an add-on, here is a MozillaZine article providing detailed instructions on how to remove an add-on, including a section on manually removing extensions from your computer.

If you are worried about messing up your Firefox installation, it should be sufficient to make a copy of your profile folder prior to deleting any extensions. If things go awry, replacing the profiles folder with the original should restore things to the way they were. The same thing applies to making a backup of the relevant registry keys prior to making changes in the registry, if you need to use some of the registry editing steps described in the article linked to above.

  • I verified this on another machine with FF 10.0.2, and my ctrl+tab behavior just moves on to the next/previous tab. Holding Ctrl+Tab does not cause a window to appear with previews of tabs and such. So this did come from an extension. – Nicol Bolas Feb 26 '12 at 0:50
  • @NicolBolas I looked into it and there is a setting in about:config called browser.allTabs.previews. If you set that to true, the preview window will appear. The default is false, though, which is probably why you ddin't see it in your tests with Firefox 10.0.2. Here is more information about it. It was introduced in Firefox 3.6. Maybe all the extension you used did, was enable and expose this hidden feature. – PersonalNexus Feb 26 '12 at 5:07

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