a) simple b) limited
The language really took off when developers took this simple limited language and pushed it to its very limits using C extensions. The data science explosion opened up the language to a very wide user base.
So to answer your 3 questions: a) Python is not a fast language by any means. There is a lot of overhead in every function call that makes it almost impossible for low latency/real-time use cases. b) I don't think Python is particularly the best language for this. This is just a demonstration of someone building their own custom toolchain to show what is possible with just pure Python. The author has highlighted why they think this is interesting on the website. c) I keep thinking Python will go away soon, and we will see a much better alternative. But the reality is Python is entrenched deeply just like JavaScript. Lot of smart people are putting in a lot of effort to make it better. Personally the ecosystem and packaging story does not annoy me much, but the lack of proper threading (GIL) has hurt my projects more than once.
For your particular pain point, the current community recommended solution is to use uv (https://github.com/astral-sh/uv). There were several detours (pip, pyenv, pipenv, poetry etc.) the community took before they got behind this.