"Why can't we have a language that compiles to highly optimized JS?" is definitely something that has crossed my mind, especially in situations where I reached for faking structs with TypedArrays. As soon as that gets more complicated than something like an array of x,y,z points things get difficult (not to mention almost impossible to debug) really fast.

I suspect that if you could come up with an easy way to express a large tree really efficiently in a TypedArray in a relatively generic way, that you already will do better than most attempted solutions here.