See it's one of those things where you can't be sure if it's sarcasm or not; I've read plenty of anecdotes where it was in fact a case of putting in sleep() on purpose (either to remove it later to show off, or because customers were complaining things went too fast), or leaving it in by accident.

Another variant is that older games (think cartridges, some CD's) had a block of unused data, so that when the game approached completion and they had to crunch to make it fit on the cartridge, they had some space left over. Probably the same for RAM memory.

I've done this.

I had to add sleep calls because the client had a simple resource consumption monitor that would complain if anything used more than 80% of the machine's CPU. Arguably a stupid policy; arguably simple enough to work.

Some time later, the client wanted the script to finish faster...so the sleep calls were deleted, and they changed their resource monitor.

I mean as an infra person I can kinda agree with this. I wouldn’t put it on the app, and would have used cgroups but I don’t want to starve OS services for cycles.