10x improvement over Go is a reasonable expectation, in a limited set of environments, generally at a scale where you're looking at using every last bit of a 32-core or 64-core machine and doing a lot of memory work. You should also expect to be spending a lot of time optimizing that Rust to get there. But when you need that level of performance, you also basically made a mistake starting with Go in the first place.
However, by far the bigger problem is people thinking their little web service serving out 5 requests a second requires that level of optimization when in fact even a Go implementation will use <1% of the CPU and no other resources to speak of. Dynamic scripting languages, IMHO, have skewed a lot of people's performance views. Go is already more power than most problems need, in terms of raw performance, and it's only a sliver, a niche where that's the difference between a Go vs. Rust choice.
It's a delicate understanding, but an important one for a professional.
However, by far the bigger problem is people thinking their little web service serving out 5 requests a second requires that level of optimization when in fact even a Go implementation will use <1% of the CPU and no other resources to speak of. Dynamic scripting languages, IMHO, have skewed a lot of people's performance views. Go is already more power than most problems need, in terms of raw performance, and it's only a sliver, a niche where that's the difference between a Go vs. Rust choice.
It's a delicate understanding, but an important one for a professional.