Firefox takes a long time to start up

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  • Creator: scoobidiver
  • Comment: rewriting the font section, renaming heading names, adding keywords
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This article describes some causes and steps to take when Firefox takes a long time to start up.

Update Firefox

Firefox 3.5 may take an abnormally long amount of time to start after turning on your computer (this is known as a "cold start"). Thus is caused by a bug which was fixed in Firefox 3.5.1. Updating Firefox will fix the problem.

  1. At the top of the Firefox window, click on the Help menu.
  2. Select Check for Updates....
  3. Follow the instructions in the Firefox Update wizard. For more information, see Update Firefox to the latest release.


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 a different website or use a blank home page. See How to set the home page for instructions.


Reconfigure 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.


Refresh the font cache

Firefox loads all your fonts using the font cache so that it can allow websites to display pages in all available fonts. At time, the font cache may be corrupted or too large. Refreshing the font cache can sometimes greatly speed up Firefox startup times.

To refresh the font cache:

  1. Close all your Windows applications.
  2. With Windows Explorer, navigate to C:\Windows\System32.
  3. Find the FNTCACHE.DAT file and rename it in FNTCACHE.BAK
  4. Restart your computer.
  5. Restart Firefox.
  6. Surf on various websites to populate the font cache again.
  7. Close Firefox.
  8. Restart again Firefox.

The easiest way to automatically reset all the font cache files in Mac OS X is to restart your computer in Safe Mode (also known as a “Safe Boot”):

  1. Shut the computer off.
  2. Press the power button.
  3. Immediately after hearing the startup tone, hold down the Shift key.
  4. Release the Shift key after the Apple logo and spinning gear (progress indicator).
  5. Restart the computer without holding down any keys.
  6. Restart Firefox.
  7. Surf on various websites to populate the font cache again.
  8. Close Firefox.
  9. Restart again Firefox.

To refresh the font cache:

  1. Close Firefox.
  2. Go to your Terminal and run: sudo fc-cache -f -v
  3. Enter your password.
  4. Once the font cache has been refreshed, restart Firefox.
  5. Surf on various websites to populate the font cache again.
  6. Close Firefox.
  7. Restart again Firefox.

The startup time should be shorter.


Disable startup-time consuming extensions or themes

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


Other solutions

None of the actions above help you to reduce significantly the startup time. Basic troubleshooting steps can help diagnose and isolate the cause of this issue.