The compiler might be rewritten in Go, but the Typescript and Go languages themselves are very different.

Go’s main objectives were fast builds and a simple language.

Typescript is tacked onto another language that doesn’t really care about TS with three decades of warts, cruft and hacks thrown together.

It's hard to say.

One the one hand the go type system is a joke compared to typescript so the typescript compiler has a much harder job of type checking. On the other hand once type checking is done typescript just needs to strip the types and it's done while go needs to optimize and generate assembly.