Super Mario Galaxy - Slowdown and audio stuttering

[JMC47]

I think you maxed it out too much in the graphical settings. I can't handle 4x IR on the same processor (Internal Resolution affects processor too! Don't forget that.) Certain games like this are really intensive like that, and max out the GPU thread on processor, or increase latency in GPU/CPU communication. So yeah, I hope that makes sense, try changing settings around.

Also, try OpenGL with that beast of a graphics card, it'll be much faster in this particular game!