Use OpenGL, Mario Galaxy doesn't like D3D11 at all, and your Nvidia + Vertex Streaming Hack will lend you much, much more speed.
And yes, your CPU is the bottleneck, but a more efficient GPU backend uses less CPU. Hopefully this can make it a bit more playable for you.
And yes, your CPU is the bottleneck, but a more efficient GPU backend uses less CPU. Hopefully this can make it a bit more playable for you.