Chalst: Oh, I didn't mean to imply the runtime costs end with the set of runtime sertives. I'm well aware that every backend "solution" for a compiler-writer imposes some constraints on the form of the translation, and hence a set of performance taxes itself. In LLVM's case, for example, it seems to want a free hand in managing your frames, and it can't guarantee you tail calls. So anything not-C-like in the control-abstraction or calling-convention requirements -- common-ish in FP -- is probably going to require more explicit heap representations of frames, or old-skool trampoline helper functions or such. These costs might be acceptable, but they're similar to the costs you face when translating many languages via C itself.