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Firefox takes a long time to start up

This article describes some causes of a long start up time and steps you can take to improve it.

Note: The Refresh Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Consider using it before going through a lengthy troubleshooting process.

Change the home page

Problems with a website can cause Firefox to take a long time to start. Try changing your Firefox home page to the default home page or a blank page. See How to set the home page for instructions.

Change how windows and tabs are loaded

If you set Firefox to use the Session Restore feature to show your windows and tabs from last time, Firefox can take a long time to start if you had lots of websites open the last time you used Firefox. You can choose to open the last selected tab only:

  1. Click the menu button New Fx Menu and choose Options.Preferences.
  2. Select the General panel
  3. Check Don't load tabs until selected so that only the last selected tab is loaded at startup (this should be the default setting).

Check your antivirus software

Firefox reads a number of files normally during startup. Some antivirus software may do intensive scans of each of these files during startup and block access until those scans complete. If the problem began after installing, updating, or reconfiguring your antivirus software, contact the software provider for assistance.

Troubleshoot extensions or themes

Firefox loads extensions when it starts up and many extensions add startup tasks. See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems for steps on how to identify an extension that may be causing the problem.

Optimize Windows

Speed up Windows and make your computer work better.

Other solutions

If the previous suggestions don't significantly reduce Firefox startup time, see Troubleshoot and diagnose Firefox problems for other steps you can take to resolve the problem.

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Version History
Revision #:
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Last update:
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See /forums/knowledge-base-articles/704895 for related discussions about this article.

This was posted in the related article discussion at so I've copied it here/

mha007 said

Hi. I have Edited the article & Submitted for Review based on the issue that users using Session Restore complain about Slow Startup because of Restoring (loading) all of the previously opened tabs and windows at the same time. Using the ' feature will result in loading a tab only when selected, thus speeding-up Firefox startup. Revision 21252 - Hope to hear from you guyz and get it approved soon.

It looks great! The only small changes I would maybe suggest would be to add double brackets around [[Session Restore]] so that Restore previous session - Configure when Firefox shows your most recent tabs and windows becomes a link to a related article. That, and using a Windows 7 screenshot, which is preferred ... but that can always be updated later. I'll wait awhile before approving this, in case someone else has any comments but as far as I'm concerned, it's good to go.

Thanks. I can put [ ] but i use Win Xp so i won't be able to upload a Win 7 screenshot..

(I deleted my last post)

I made a new revision to create a "Change how windows and tabs are loaded" section, after "Change the homepage", since I just noticed that the information overlaps. I also added a Windows 7 screenshot for fx8 and above showing the "Don't load tabs until selected" feature which, I now see, is only available in Fx8 and above. Needs review.

mha007, what do you think?

seems much better than mine :D good to go..

Thanks. I approved it but didn't mark it as ready to localize, in case we missed something that needs to be added.

And discussion thread about including advice on Hardware acceleration


I want a link that dose it all. I follow theses around and do not know what to do with most and get lost in it.

Try this:

It will remove any extra things from Firefox like your addons. But it will keep your important stuff like passwords, bookmarks and browser history. The other things will not be carried over.

If this doesn't work, please use this link to post your problem to our support forums:


It seems that one user has edited and fixed a small grammatical error. That's why this document is now not ready for localization. I compared it with the previous revisions. seems like it's a small edit. So, mark it as localization ready, if possible.

I marked the Jun 16, 2013 edit as ready to localize.


I am more then disappointed in Version 29. I lost half of my ad ons, I lost the add on tool bar, etc. to say that this FF is not very good is mild to the way I view it. I went back to 28 in five minutes. 29 sucks!

I made a revision to the "Optimize Windows" section to make it {for winxp,win7,win8}. I self-approved it, based on a similar update to the "Optimize Windows" section in the Firefox is slow - How to make it faster article.

I set up a "Needs change" entry to update the section for Windows 10 and link to a support article (possibly if we can't find a Microsoft article). Related discussion:

I have an edit pending to add a link to for win10.

AliceWyman said

I have an edit pending to add a link to for win10.


I got a PM that the tenforums page isn't localizable. I set up this Needs change entry:

"Optimize Windows" section needs a better link for Windows 10, ideally a Microsoft Support article with localized versions.