The parser written in Go was both faster to compile and faster to execute than the parser in Rust. The Go version compiled something like 100x faster than Rust and ran at something around 10% faster (I forget the exact numbers, sorry). Based on a profile, it looked like the Go version was faster because GC happened on another thread while Rust had to run destructors on the same thread.
The Rust version also had other problems. Many places in my code had switch statements that branched over all AST nodes and in Rust that compiles to code which uses stack space proportional to the total stack space used by all branches instead of just the maximum stack space used by any one branch: https://github.com/rust-lang/rust/issues/34283. I believe the issue still isn't fixed. That meant that the Rust version quickly overflowed the stack if you had many nested JavaScript syntax constructs, which was easy to hit in large JavaScript files. There were also random other issues such as Rust's floating-point number parser not actually working in all cases: https://github.com/rust-lang/rust/issues/31407. I also had to spend a lot of time getting multi-threading to work in Rust with all of the lifetime stuff. Go had none of these issues.
The Rust version probably could be made to work at an equivalent speed with enough effort. But at a high-level, Go was much more enjoyable to work with. This is a side project and it has to be fun for me to work on it. The Rust version was actively un-fun for me, both because of all of the workarounds that got in the way and because of the extremely slow compile times. Obviously you can tell from the nature of this project that I value fast build times :)