[mistercow]

I don't think that added complexity invalidates the usefulness of high performance APIs in high level languages. The point would not be to write all of your code to be highly performant (that would be premature optimization), but to optimize the hot spots.

Currently, if you want to really optimize a hot spot in, say, Python, your only real option is to write that part in C. Then you have all the additional complexity of gluing that into your Python program, along with portability concerns and a more complex build process. It would be so much easier if there were a way to sacrifice local simplicity and idiom for performance while still staying in the language.

And in the case of JS, I'm not sure you have much in the way of options at all for optimizing hot spots to reduce allocations. Maybe you could write it in C and compile it to JS via emscripten? I don't know if that would even help currently, but maybe if asm.js takes off. But once again, wouldn't you rather sacrifice a small amount of elegance for performance rather than switching languages?