I feel like he jumped into "hard" optimisation too fast.

I would say when you find code running slow, first you do:

• only do nessesarry work, if we only need to look up a persons name we do not need to load all and everything and their image for that person from a DB, File or alike (fewer calls)

• dont do the same work twice, if you already calculated something you might not need to calculate it twice (example: caching)

then if perfromance is still an issue, do what he suggests in the article :)