If the slowest part of your program is waiting for RAM to get into your CPU registers, then you have one of the most blazingly fast programs ever written. Grats

If the slowest part of your program is waiting for RAM to get into your CPU registers, then you have one of the most blazingly fast programs ever written. Grats! The vast majority of software has much, much, much lower-hanging fruit than that: things like O(n^2) algorithms where O(n) exists, SELECT N+1 issues, missing database indexes, missing easy wins with caching, repeated work, threads blocking each other, loading more data than necessary, throwing and then suppressing exceptions everywhere, bad netcode, doing work serially that could be paralyzed, etc. In this software, fixing these issues will be 10x easier and result in 10x larger speedups than worrying about organizing your data to get loaded from RAM into CPU caches more quickly. That makes this advice counterproductive for most programmers to hear.