It would suggest to me that something in your login items is not compatible with Snow Leopard.
If you don't have a second account then create one.
Login using the second account and see if it is quicker on a 'clean' system.
If it is quicker, note what the standard login items are then reboot into your original account and see what extra login items you have.
Let us know how you go.
Ever since I installed Snow Leopard, once start-up is complete, I am not able to use the keyboard or track pad button for about 3-4 minutes. They are frozen - the cursor/arrow move according to trackpad/mouse movements, but anything kind of button/key input is not registered.
I have plenty of space on the hard drive - a suggestion that someone made on another forum. I have seen about 2 or 3 other posts of people reporting similar issue, but never seen a resolution.