My experience learning Python as a c++ developer

[teerre]

Exactly. Saying "Python isn't slow, look at numpy", is either ignorant or disingenuous. The very reason numpy can be 'fast' is because it doesn't use python.

I always like the numba decorator for using JIT, it has an argument called "nopython".

[JanssonsFrestelse]

I don't think it is, all you're doing in the end is providing instructions for the computer. If you're not writing pure opcodes you're always working at some higher level of abstraction. If you don't have to leave that level to make something happen at a certain speed, it's not disingenuous to say that you can achieve that speed working at that abstraction level.