History suggests that, for a good approximation of the truth, the resources put into a language implementation (and, in particular, into JIT compiling VMs) strongly correlate with its performance. So V8 and HotSpot, for example, both have great performance -- and both have had large teams working on them for many years.

Interestingly, PyPy has pretty decent performance despite having had a much smaller team working on it, mostly part-time. An interesting thought experiment is whether similar resources put into PyPy -- or a PyPy-like system -- would achieve similar results. My best guess is "yes".