When using the start menu the you will notice a delay between different tiers of the menu hierarchy.
To make this showing a bit faster you may make the following edit's.
Start>Run> Regedit. click Ok.
Navigate to HKEY_CURRENT_USER\Control Panel\Desktop
Select MenuShowDelay from the list on the right.
Right click on it and select Modify.
Change the value to something lower (note: a setting of zero (0) is virtually instantaneous - experiment with other settings (100 or 75 or 50 perhaps) to see what you are most comfortable with..
Reboot your computer.
I have mine set at 155..