You can speed up the loading of Firefox on Windows XP by adding it to the programs that XP "prefetches."

To do this, right-click the Start Menu item for Firefox, or any icon you use to start Firefox, and open the Properties dialog box. Add a space plus /Prefetch:1 to the command line and click OK. The resulting line might look as follows:

"C:\Program Files\Mozilla Firefox\firefox.exe" /Prefetch