It's very system dependent, but VoltDB is designed for systems that require up to a million tps. "A matter of ms" is not irrelevant in such systems.
But micro optimization has always the same caveat:
Of course it is not irrelevant, it might even be very important, in very specific cases.
But if you are not one of those cases (and you should already know if you are) you shouldn't even bother with it.