And now they have to manage register pressure for it to keep being faster. And false dependencies. And some more. It doesn’t work like that. Developers can’t optimize like compilers do, not with modern CPUs. The compilers do the very heavy lifting in exchange for the complexity of a set of constraints they (and you as a consequence, must) rely on. The more relaxed these constraints are, the less performant code you get. Modern CPUs run modern interpreters as fast as dumbest-compiled C code basically, so if you want sensible semantics, then Typescript is one of the absolutely non-ironic answers.