I've just integrated SassAndCoffee into a project. It works great, with the exception of debugging. A single request to a .scss resource returns in 50ms. Hit F5 and refresh, and the exact same request takes 1300ms. (I'm measuring second request oneward of course - first request takes longer for other reasons).
Using dotTrace, the culprit appears to be IronRuby:
Is this a known issue? Is there some fix for this?