> I did some of my own benchmarks and Go and D turned out faster than Rust, or at least their maps/associative arrays are faster that Rust's HashMap. Also, I won't use stuff that is not in the stdlib in the benchmarks.

Rust's HashMaps are intentionally slow by default. You could use a different hash function with them if you want different properties. That means writing your own if you don't want a known-good implementation, of course, but this is expected and not really representative of Rust generally, which uses associative arrays pretty infrequently.