In machine learning for trading class, a python for loop code was turned into numpy array where the code went from something like over 4 minutes to a few millis

In machine learning for trading class, a python for loop code was turned into numpy array where the code went from something like over 4 minutes to a few milliseconds. Its astounding how much you can improve on code just by a vastly better algorithm. Note: I know numpy is C and faster than python but that was not the point. The point was using vectors vs bruteforce.