When using the start menu the you will notice a delay between different tiers of the menu hierarchy. For the fastest computer experience possible I recommend changing this value to zero. This will allow the different tiers to appear instantly.

Click start>then run, and type regedit and enter ,then
Navigate to HKEY_CURRENT_USER\Control Panel\Desktop
Select MenuShowDelay from the list on the right.
Right on it and select Modify.
Change the value to 0
Reboot your computer.