The author claims that making better use of the cache hierarchy and programming in a data oriented way will improve perceived performance for users. This isn't where we should start though.

Much of the time bad performance comes from excessive I/O, bad algorithms and data structures (e. g. accidentally quadratic code), or misuse of third party libraries or services. Eliminating problems like this needs to come first and only then is it reasonable to consider the cache-friendlyness of our code.