Unlike PC games, Wii/GC games needs to run at a certain FPS (Most of them 60 FPS) to go full speed, they can't adujst the framerate to your hardware's capasity. So with 38FPS out of 60FPS in Mario Kart Wii, your game will run at 63% of normal speed. Try doing a speed test 1p race, you'll probably get fullspeed there.
Specs: intel i5 3570k @ 3.4GHz;
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
