A simple Registry tweak can give speed up your start menu and sub-menus. Open the Registry Editor, and navigate to and select:
HKEY_CURRENT_USER\Control Panel\Desktop . Double-click the MenuShowDelay icon on the right, and change 'Value data' from its default of 400 (milliseconds) to something speedier, like 0. When you have finished, press Enter.
"Windows XP Tips: A Flying Start for the Start Menu"
Reference : techpraveen.com