Dolphin, the GameCube and Wii emulator - Forums

I'd say it's a combination of a) wrong adapter selected in the graphics configuration b) the nvidia driver being stupid again and using the wrong GPU for Dolphin (which could be resolved by forcing Dolphin into high-performance mode from the driver).

Neither of those things has anything to do with adding a second cpu. He said that ever since he added a second cpu dolphin has become slow on d3d11 and openGL but not d3d9.