Rust is actually few steps above from the bare metal, to enforce its security invariants. Boundary checks (which breaks auto-vectorization of loops), stack probe, fat pointer (wastes register), fixed index type (uint), etc.

There are other hidden costs coming from usage of std. Even `Result` is a bit of inefficiency.

I'm not saying any of these are bad. I'm just saying Rust would be slower than C if *naively* used.

Okay, cool, I can see where you're going with this. I wouldn't exactly agree, because all of these things are stuff you can easily opt out of, but I thought you were maybe suggesting something like "the borrow checker has overhead" which I would take more direct issue with.

(and yeah, the opt out question gets right to what you're saying about "naively used", I saw "unavoidable" but you're not actually saying it's unavoidable.)