Default Received today new galaxy s and I want to flash it

Hi,

I received my galaxy s today and I realy like it. While using it I saw much things get a lil laggy like app market. I want information for the best Rom/Kernel and how I have to flash it. The phone doesn't have CWM or something its just new with the original android froyo. I want to make it fast and let it have more ram free and maybe overclock it an bit.

So please tell me whats the best to do and give me some guide to flash.

David