Currently Being ModeratedJan 3, 2013 5:22 AM (in response to berkeo)
First look at your login items, ensuring that they run with Mountain Lion or are at least the current version. Same thing in the System Preferences window, look at the bottom for any software listed, and ensure each runs with OS X 10.8, or is at least the most current version.
You can install an SSD (solid state drive) in place of your hard drive. That will dramatically speed up your boot up speeds.