The Rust for Linux project

My gut feeling is that it is more around figuring out what the optimizer can help out with. Rust can probably optimize iterator method chains far better than C's loops, but at that point, you're also fiddling with details that affect the inline heuristic engine and other such details that vary between compiler implementations and versions of the same compiler, so even there I'd think that "what my specific compiler does" may not be suitable because the optimization could fall on the other side of the line in the next release too.