Typescript is being natively ported to Go. This makes it 10X faster. Half the memory use.

[pcchen]

So a programming language is being ported to another programming language that doesn't make sense
a bit like saying C++ is is being ported to Fortran
Edit: think I understand now, the language isn't being ported, the compiler has been re-written in Go

Yes. The reason why it's better to have a fast Typescript compiler is not just because of building times but also because many tools (such as the IDE) uses the compiler quite frequently. So the ability to quickly launch the compiler many times can improve the responsiveness of the IDE for quite a bit.