Yes, I noticed this too while writing the points down. It really comes down to the clang back-end. I'm really looking forward to the clang integration in VS, and also really love the work MS is doing to fix Android native development.

One strange thing I see with clang running on Windows (in the form of the emscripten fastcomp backend) is, that clang runs a lot slower on Windows than OSX or Unix. So may be it is some underlying IO problem? I'm not sure but hope this can be fixed.