You can use this tip to speed up the Start Menu in Windows XP release candidate 1. You can customize the speed of the Start Menu by editing a Registry Key.
Click Start, and then click Run.
Type Regedit in the box, and then click OK.
Expand the menu in the left panel and select the HKEY_CURRENT_USER\Control Panel\Desktop folder.
Scroll down in the right panel and double click on the MenuShowDelay file.
In the Value Data box, change to default value for the menu speed from 400 to a lesser number, such as 1.
Click OK.
Caution: Incorrectly editing the registry may severely damage your system. Before making changes to the registry, you should back up any valued data on your computer.

Reposted from Digital Port XP
Original Article by helslayer