[Manishearth]

Java/Go use a GC and have certain design principles which place an upper bound on the speed unless you want to break backwards compatibility.

Rust does not. The main issue with Rust is that we haven't gotten around to optimizing the IR properly. It's something which can be done backwards compatibly without changing the actual language at all.

The only design component I can think of which leads to bad perf is the drop flag. And that's something that should go away soon (Rust doesn't guarantee that destructors will run using this model only, so it can be changed)