That's strange. You'd think the collision would go higher than the mesh. Correction for collision, Nate's imported a map that was about 4,800 polygons and it ran fine on my computer (granted it's uber overkill for N64 games but still). Mesh was basically the same, iirc.
If it's a problem with cache, I'd assume it's probably an error more to do with your installation of Python than the script itself. Try reinstalling Python, make sure it's v 2.5 or 2.6 (the latest of whichever you choose to install). Failing that, I'd take your question directly to spinout.