It sounds like they're talking about HTTP requests/responses, then that sounds mostly like just networking overhead, and it wouldn't matter if it was JS/Go/Rust or C++, network latency would be there anyways. And if that's with network latency excluded, just hitting localhost, then that sounds horrible, should easily be below 1ms unless you're doing something heavy, but sounds like a typical application with no such actions.
Rust is not the reason you have sub-100ms response times. If it were the true bottleneck your app would be far faster than this