As always, it depends on what your goals are. String processing is usually not the long pole when you're building something that consumes the output of a parser. Based on micro and macro benchmarks, Rust is typically substantially faster than Go and pretty much always uses less RAM [1].

But again, depends what you're doing with the output, and if these deltas even matter in your context.

[1] https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

You can write a parser as far as the limits of your imagination allow in Rust, or C, or any other baremetal language without a thick run-time.

In Go, beyond the limits of your imagination, you'll also hit other limits, like those of the garbage collector.