MB13,3" 2009 May/April - Slow.

Hi,

New to these forums. Just been searching on google somewhere i could get a solution to my problem.

The problem:

Macbook, 13,3" early 2009 with Snow Leopard installed.
When ever i play WoW(Warcraft) with safari on the background, or Photoshopping with safari on the background it goes dead slow. Example playing youtube movie clip its like its a slideshow.

I've been running updates for the passed 2 weeks hopefully trying to get an update or if it was a bug or not but i couldnt find anything.

Before i installed snow leopard i could open 3 World of Warcrafts + safari open no problem (low settings ofcourse.) But now it even struggles with 2 without safari opend.

I would like to know how to find a solution to this,

Thanks allot.