Pretty impactful work for an intern! One thing I would have liked to see, both from a process and communication standpoint, is leading with some stats on how much faster the vectorized loops are in isolation from the surrounding engine.

It's always good practice to dig into a deep project like this with some napkin estimates of how much you stand to gain, and how much overhead you can afford to spend setting yourself up for the faster computation. (Not to mention how much of your own time is merited!)