Zlib-rs is faster than C

        unsafe {
            let x_tmp0 = _mm_clmulepi64_si128(xmm_crc0, crc_fold, 0x10);
            xmm_crc0 = _mm_clmulepi64_si128(xmm_crc0, crc_fold, 0x01);
            xmm_crc1 = _mm_xor_si128(xmm_crc1, x_tmp0);
            xmm_crc1 = _mm_xor_si128(xmm_crc1, xmm_crc0);

Presumably with inline assembly both languages can emit what is effectively the same machine code. Is the Rust compiler a better optimizing compiler than C compilers?

The Rust compiler is indeed better than the C one, largely because of having more information and doing full-program optimisation. A `vec_foo = vec_foo.into_iter().map(...).collect::Vec<foo>`, for example, isn't going to do any bounds checks or allocate.

> isn't going to do any bounds checks or allocate.

You need to add explicit bounds check or explicitly allocate in C though. It is not there if you do not add it yourself.

Yes — in C you can skip the bounds-checks and allocation, because you can convince yourself they aren't needed; the problem is you may be wrong, either immediately or after later refactoring.

In other memory-safe languages you don't risk the buffer overrun, but it's likely you'll get the bounds checks and allocation, and you have the overhead of GC.

Rust is close to alone in doing both.