[heffo]

I believe that the author meant to write 0.25 seconds, instead of 0.5 seconds. She says that the one step halves the running time, and later on she is investigating how the 0.25 seconds are split up.

A >50% speedup is not to be sniffed at! I completely agree with your point though, unless it is mission critical that this code runs as fast as possible, then you are better off keeping it simple!