Python will be much slower than C, but if you follow the path that you suggest and use Python mainly as glue to stick C-based performance critical parts togethe

Python will be much slower than C, but if you follow the path that you suggest and use Python mainly as glue to stick C-based performance critical parts together you could be fine. I used to edit an HPC trade rag, and I've written a lot of performance-critical code in C and C++, and even in Java eg for high-speed trading. As a now-old fresh PhD student I think that your profs are probably wrong!