I'm an old PhD student. I've seen cases where an easy / naive solution written in Python can be orders-of-magnitude slower than a solution written in C, but I s

I'm an old PhD student. I've seen cases where an easy / naive solution written in Python can be orders-of-magnitude slower than a solution written in C, but I suspect that you're right: that a thoughtful / clever use of Python should be perfectly fine. I've also seen that professors don't know everything, and what they do know can be dated. More importantly, though, I think a young PhD student should not pick a fight with his advisor and committee members or try to prove them wrong. Generally, do what they suggest and give them credit for it, or at least thank them enthusiastically for the suggestions and don't make a big deal about not following them. You're at their mercy for getting the PhD, and it's subjective, and their opinion of you probably matters at least as much as their opinion of your work. This is one the things that I learned from ~15 years of professional work under many different bosses before starting my PhD program, and something that I think many young students still need to learn.