Firefox takes a long time to start up

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  • Revision id: 21252
  • Created:
  • Creator: Hasan
  • Comment: Using the '''Don't load tabs until selected''' feature will result in loading a tab only when selected, thus speeding-up Firefox startup.
  • Reviewed: No
  • Ready for localization: No
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This article describes some causes of a long start up time and steps you can take to improve it.

Configuring session restore

If you use Session Restore, then by default when Firefox starts, Firefox opens all windows and tabs from your previous session. However this behavior can slow-down your Firefox at startup if you have a lot of tabs and windows opening at the same time.

Restore Previous Session - Win5 Fx9
Restore Previous Session - Win5 Fx9
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To resolve this issue and speed up the startup:

  1. In the Menu bar at the top of the screen, click Firefox and select Settings (select Preferences on older macOS versions).Click the menu button Fx89menuButton and select Settings.
  2. Select the General panel.
  3. From the When Firefox starts drop-down, select Show my windows and tabs from last time and check Don't load tabs until selected so that only the last selected tab is loaded.
  4. Close the Settings page. Any changes you've made will automatically be saved.

This change will result in loading a tab only when selected, thus speeding-up Firefox startup.

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.

  • If you set Firefox to show your windows and tabs from last time, check Don't load tabs until selected in the General panel of the OptionsPreferences window so that only the last selected tab is loaded at startup.try to use Tab Groups so that only websites in the visible tab group load first.

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. See Optimize Windows 7 for better performance where some recommendations are also applicable to other Windows versions.

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.