Firefox takes a long time to start up

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  • Revision id: 11412
  • Created:
  • Creator: Tonnes
  • Comment: minor nits
  • Reviewed: Yes
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  • Reviewed by: scoobidiver
  • Is approved? Yes
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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.


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.


Use Windows Update to install a fix from Microsoft

This section only applies to Windows 7 or Windows Server 2008 R2.

Microsoft has released the recommended KB2505438 update that fixes slow startup performances in Firefox when HW acceleration is enabled. To make sure, you have this update installed:

  1. In Windows, click Small Vista Logo, select All programs, then select Windows Update. The Windows Update window will open.
  2. Click the "Check for updates" link and wait until it is done.
    • If no updates are available, you have this KB update installed. Skip to the next section.
  3. Click "n optional updates are available". The View available updates panel will appear.
  4. Click "Optional" and search KB2505438 in the list.
    • If you don't find it, you have this KB update installed. Skip to the next section.
  5. Check it and click OK to close the View available updates panel.
  6. Click Install updates.
  7. Restart your computer.
  8. Start Firefox and check if it loads faster.


Other solutions

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