I was lucky enough to come upon a similar speedup in some code that was used a fair bit at first job; multiple order of magnitude speed up by applying some data

I was lucky enough to come upon a similar speedup in some code that was used a fair bit at first job; multiple order of magnitude speed up by applying some data structure knowledge. I feel like base level algorithm/ds knowledge is getting higher so these will disappear, even if you don't know the exact solution your intuition will make you think "there's no way this needs to be so slow" and then you do some research/thinking.