alt Hacker News> Saying it can't be fast ever is a huge cop-out.
Maybe, but the world is still waiting for the counterexample. Python is simply not a runtime well-suited to optimization.
In the meantime, those of us who actually enjoy real HPC problems are using numba and rolling our eyes about all the confuffery around JITs. Maybe one will arrive that proves us wrong, but numba is fast today.
LuaJIT has the same dynamism with dictionaries and it's very fast at accessing them in JIT code.
I don't have enough experience with PyPy to say much about it.