As for startup speed, note that in this round our research software engineer in the Julia Lab just brought the "first time to plot" to about 1/4 of what it was before. Julia 1.3 has a lot of these updates, and Julia 1.4 has a development sprint for bringing down the latency. I would be surprised if the common major latency issues still exist past next summer. Of course a JIT will always have some bumps compared to a pure interpreter, but Julia's compiler is definitely getting a lot smarter as to what to try and fully analyze (and what to cache)