Yes, this was my takeaway - it was a very poor choice of example, because a known faster algorithm will crush the sort of micro-optimizations done here and be more readable.
Or perhaps it was actually an incredibly good example, despite itself: a great illustration of precisely why jumping to micro-optimization isn't always the right solution.
This is also a problem where the algorithmically fastest solutions are also pretty much guaranteed to be faster, since they are equally cache-friendly and will almost always work out to fewer instructions.
That is not always the case, but this is one of the times when it is.
Or perhaps it was actually an incredibly good example, despite itself: a great illustration of precisely why jumping to micro-optimization isn't always the right solution.