choppy gameplay

Hi I installed dolphin on my brand new PC the other day. I start Wind Waker . The menu and intro load fine and smooth, but as soon as I get to actual gameplay, the game gets incredibly choppy , the FPS drops to about 10 or so and the game is pretty much unplayable. Same thing happens when I try other GC games. I haven't tried wii games yet. Does anyone know what to do? I'd like to play games smoothly , if possible or at least gc games, are there any settings I have to configure and how ? I usualy leave them on default , but I did mess with them to see if it changed anything , except it didnt.Is there anything to do about it ?
My full PC specs are :
Intel i7-3630QM CPU clocked at 2.4ghz.
8.00 gigabites of RAM
The CPU is x64, running Windows 8.
Graphics card: Nvidia GEFORCE 740M