Well:
xslimmer
clean my mac
These are a view programs but there are also many free ones as well.
You could also try resetting you ram. To do this follow these steps:
1.Shut down the computer.
2.Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3.Turn on the computer.
4.Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
5.Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6.Release the keys.