Using an old version of Firefox

If Firefox is taking an abnormally long amount of time to start after turning on your computer and you are using Firefox 3.5, the most likely cause is a bug that was fixed in Firefox 3.5.1. Updating Firefox should resolve 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.

If you have updated Firefox and it still takes a long time to start up, some other causes are given below.

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.

Large numbers of fonts

Firefox loads all your fonts so that it can allow websites to display pages in all available fonts. Having large numbers of fonts can slow down this process. Removing unused fonts can sometimes greatly speed up Firefox startup times.

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 causes

Basic troubleshooting steps can help diagnose and isolate the cause of this issue if the above steps don't help.