> optimizing for compiler performance feels straight out of the 80s
I think you're misunderstanding this situation based on the suggestive word, "compiler".
TypeScript's type system is Turing-complete. That means you can theoretically write programs with the type system that cause the compiler to never complete.
Instead of thinking about this as optimizing a compiler, think of it as optimizing runtime performance of a program by better understanding the language that the program is written in.
