Click you the Start bar and click on Run
type in Regedit and then ok
Find the following key: HKEY_CURRENT_USER
Click the plus sign next to it and then scroll down until you see Control Panel, Click again the plus sign to expand it and then click on Desktop
Then in the main Registry box click on (MenuShowDelay) Click on that and select Modify and in the Value data box enter any number betwwen 0 and 400.
400 is the default setting so if you choose any number below this you can increase the speed of the start menu.
Experiment a bit here, If you choose a low number you may find it's a bit too fast for your liking.