Probably the problem with your perspective is that you're still thinking about JS "interpreters", when we don't generally have those any more - we have JITs that compile JS to machine code.

`new Foo()` is faster because it can be compiled to more efficient code today and probably always will be. Your argument is a bit like the "given a sufficiently intelligent compiler" one, I don't care about what JS engines of the future might do, I care about my code's performance today.