I would argue if you're doing performance sensitive work in that fashion, you're doing it wrong. I'd also probably argue that if you're doing it that way, you'

I would argue if you're doing performance sensitive work in that fashion, you're doing it wrong. I'd also probably argue that if you're doing it that way, you're probably already not that concerned with performance to the degree where losing a few tens of seconds is a big deal. I certainly wouldn't include any tight bash loops that execute external code in any service code, for example. Performance there shouldn't be impacting either the sync or async path. Much like the article's point, it's a question for optimising for the right things. I do agree that people can perceive values faster than 100ms. Several years back I was interviewing for a sysadmin job at a futures trading company. Part way through the interview, one of the traders complained to the interviewer that the latency was increasing on the connection to the exchange, and sure enough it was up 20ms from normal (I forget the normal, but it was very low, on the order of only maybe 10-20ms) and monitoring was just about to page the interviewer.