I have dolphin emulator 4.0.2 with melee and I was wondering why the game is so laggy for me. I have a ATI Radeon HD 4200 graphic card and AMD Phenom II X2 521 3.50 GHz processor. On a window 7 x64 bit computer. PLEASE TELL ME!
Upgrade to the latest development build and see how it runs then.
AMD+AMD，that is the key，am i right？
First of all, as OatmealDome suggested, definitely try the latest dev revision and see how it goes. But other than that, it's a well-known fact that AMD CPUs are very bad for Dolphin compared to Intel CPUs of the same clock speed. I'm no expert, but I think yours should be powerful enough to run a lightweight game like Melee (although is is only dual-core). Other than that, what are your graphics settings?
In this case the game the OP wants to run isn't that much of a problem for their CPU.
Please upgrade to the latest development build, set your graphics backend to Direct3D, and try it at 1x native internal resolution. If it works there, bump the resolution higher for your tastes.