On my Macbook, Firefox is slow. Really slow. It takes about 30 minutes to start up - when I wake up, I start it, and once I am done breakfast, it's usually done. And, it takes a super-duper long time to shut down - I haven't shut it down one, I just force close it now because it takes so long. It shouldn't be - the rest of the applications on this machine are really fast, and Safari starts instantly - but I love Firefox and don't want to leave it. How can I fix this problem?

Edit: I disabled all extensions which makes it start up almost instantly now, but it still will not shut down.

6 Answers 6


30 minutes to startup means there is something wrong and my first guess would be an extension that does not behave. I would try to disable all extensions and see if it is still slow.

The easiest way to do this is to start Firefox in safe mode. Here is quote from the mozilla support site how you can do this on your Mac:

  1. Close down Firefox completely:
    On the menu bar, click the Firefox menu, and select the Quit Firefox menu item.
  2. Hold down the Option key, as you start Firefox
  3. Firefox should start up with a Firefox Safe Mode dialog.

If that helps you can start in normal mode and disable your extensions one after another until you find the culprit.

If it does not help I would try to start Firefox with a fresh profile:

  1. Close Firefox and backup your profile
  2. Start Firefox (it will create a fresh profile)
  3. Restart Firefox to see if the problem still exists
  4. Close Firefox and restore your profile

Backup and restore of the profile is really simple, there is a detailed explanation at mozilla's support site.

  • 1
    It starts up instantly now, but won't shut down. Commented Jul 15, 2009 at 19:08
  • Hem, is there an error message or does it just hang? Commented Jul 15, 2009 at 19:22
  • 1
    It just hangs... Commented Jul 15, 2009 at 20:55
  • 3
    I deleted the whole Application Support folder. That fixed it. You put me on the right direction by deleting the profile. Thanks. Commented Jul 21, 2009 at 2:57

You might be (have been) suffering a really large places.sqlite file (holding your bookmarks and history, which may already have expired). You can compact that:

Quit Firefox, wait until you're sure it's no longer running, and then:

cd ~/Library/Application\ Support/Firefox/Profiles/*.default/
ls -lh places.*
sqlite3 places.sqlite "vacuum;"
ls -lh places.*

When the cd-command fails, the 3rd line will in fact create a new 1024 byte database file places.sqlite in the current folder. That file is not used by Firefox of course, so may be deleted.

  • I just got rid of the whole profile folder. Commented Jul 15, 2009 at 21:03

I had exactly the same problem with Firefox on a MacBook. I had no extensions for Firefox, no specific extra downloads, so that I could not say what was causing the problem by doing a safe mode start up.

I backed up my profile, and removed two files from my profile folder: the places.sqlite, which was like 8Mb then 3Mb after the vacuum command (it did not help by the way), and the urlclassifier.sqlite, which was like 5Mb.

And now, everything works like before. And I did not lose any bookmarks or toolbar bookmarks.

I don't know how Firefox uses these files but perhaps they should be cleaned off from the profile folder once every few months to keep Firefox in good shape.


Don't forget to check for file associations to make sure no users file have melted for firefox files. I'm saying this because the best way I've found to make firefox faster was to create a new profile on my macbook

  • Uninstall Firefox
  • Remove your profile (and all extensions with it)
  • Make sure you have the latest Firefox http://getfirefox.com
  • Double check that all extensions are gone. If not, delete them.
  • Check to see if speed has improved.

  • No speed improvement? I can't help you then, must be something specific to your computer.

  • Yes, speed improvement? Start reactivating necessary extensions, checking the speed after each activation. Find the culprit and banish it.

Less extensions = more speed

  • Note that your profile contains your bookmarks, saved pws and other personal data. It's not a good idea to blindly delete it.
    – sleske
    Commented Feb 11, 2010 at 23:14

You could try using Firefox's Refresh Feature which performs a bunch of cleanup operations. It can be accessed via the link or may be accessed from the about:support (this needs to be typed or copy/pasted into a new tab/window) page which also handily lists a range of details such as installed extensions and modified about:config options which can also cause issues. If you want to keep a record of your config you can just save the content of about:support page as a web page before you perform the refresh. Also beware that the 'refresh' wipes your client certificate store (it is mentioned on their webpage) so make a copy beforehand.

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