Why Photoshop and Illustrator CS6 are so slow on my MacBook Pro early 2011?

First of all sorry for my english

I recently installed Photoshop and Illustrator CS6 and they tend to lag even on just during normal work operations like zooming, opening a file, selecting a tool, browsing menus etc etc.

Cpu, Ram and Gpu usage are normal, I mean when I use these software there's at list 85% of free Cpu, 1GB of Ram still available, and 80% of free GPU. And I got 30GB left on my hardrive which is little but I believe is enough.

So I cannot believe this slow performance is due hardware limitations. There must be some driver issue or something else.

Anyone knows why CS6 is so slow?

Software version:

Photoshop CS6 13.0.1

Illustrator CS6 13.0.0

My Specs:

Os: Snow Leopard 10.6.8

Cpu: Intel Core i7 2.3 GHz

L2 Cache (per Core): 256 KB

L3 Cache: 8 MB

4GB ram

AMD Radeon HD 6750M