Exciting changes for python

I've found that to be very true, the first draft of code often lives for years if it works but can be very meandering as the initial developer figured how to solve the problem as they went, once you know what the output is supposed to be refactoring it can be as simple as replacing many loops through a data set one loop checking multiple conditions or a hash key lookup replacing a complex set of expressions, sometimes made easier by a simple reformatting of the input data to make it easier to look up. The end result is asking the computer to do much less work which is almost always faster and as you say, doesn't require deep microarchitectural knowledge, just a basic sense of proportion.