Hi Alyssaanne,
The suggestion to add more memory is not a bad one. LimeWire uses alot of memory on a Mac. I added 256MB to my 128MB and it improved. Not greatly, but it does run smoother. I am able to run (some) other programs while running LimeWire now. I try not to run anything else, usually, because of conflicts, but it is now possible. You can get some real cheap memory upgrades at Costco (if you have access to one).
Good luck.