I bet if you compared single threaded performance you’d still blow Babel out of the water. Even with the best JITs, idiomatic js code is so much harder/impossible to optimize than idiomatic rust or c/c++ code.
I think Babel 7 had some perf improvements (including tweaks contributed by Benedikt Meurer from the v8 team), but I don't think they've ever had time to focus on just improving perf.
It's true, speed is not really a concern on my mind at the moment - rather that we have enough people even willing to contribute back at all