Zig seems to be a good choice here.
So why not something like OCaml that has fast compile times and a lot of nice features for writing compilers? (pattern matching, etc.)
This includes the Roc compiler too. Zig is significantly faster than OCaml.
A Roc compiler written in Zig would compile Roc code significantly faster than a Roc compiler written in OCaml.
GCed languages can be fast, probably even as fast as any of the aforementioned languages with enough engineering effort, but in terms of high performance, it's actually easier to write high performance code in the aforementioned languages rather than in a GCed language.