You just opened the box of pandora for a million reasons most of which are unbeknownst to the both of us :) But for the sake of argument I will continue under this assumption

> language to be about as fast as possible

If you're interested in Mathy stuff like Machine Learning, FFT, ... then maybe. But even for those you usually have JNI bindings, so it's easy to use most of those mathy C libs if necessary.

But I guess that 95% of all software isn't about speed but about something else (correctness, maintainability, safety against threats, portability, ...) because costs today are usually dictated by manpower costs or those arising from safety/security incidents and much less often by hardware costs compared to say a decade ago.