Why Python Loops Are Slow (And Why NumPy Is Fast)

You can write two pieces of code that do the same math, produce the same result, and look almost identical, and one will be 10× to 100× faster. This video explains why that happens, without hand-wavy answers like “NumPy is written in C” or “Python is interpreted.” We’ll break down what actually runs when you write a Python loop, what changes when you switch to NumPy, and why the real difference has nothing to do with smarter algorithms. The key idea is execution: where the loop runs, what work is done per element, and how much of that work has nothing to do with math at all. By the end of th…