I had the same thought. A direct port of tsc to a "faster" language doesn't guarantee a faster type checker. Sure it might be a bit faster, but my guess is tha

I had the same thought. A direct port of tsc to a "faster" language doesn't guarantee a faster type checker. Sure it might be a bit faster, but my guess is that the large performance wins come from a different design that takes performance into consideration from the start. Maybe the thought process is that a 1:1 rewrite will handle compatibility and feature completeness? I suppose you could optimise from there?