I'd love to see someone develop a compiler for TypeScript that got, say, Ocaml-like performance. There's a bunch of reasons why that'd be tough though - you'd probably want a language very-similar-to-but-not-quite-like-TypeScript.
You can't synthesize ad hoc union types (https://www.typescriptlang.org/docs/handbook/2/everyday-type...)
There's no notion of literal types (https://www.typescriptlang.org/docs/handbook/2/everyday-type...)
There's no type narrowing (which gets you a kind of sum type) (https://www.typescriptlang.org/docs/handbook/2/narrowing.htm...)
Most of the type maniuplation features (keyof, indexed access types, conditional types, template literal types...) are missing (https://www.typescriptlang.org/docs/handbook/2/types-from-ty...)