The Fallacy of Premature Optimization (2009)

There's an interesting talk by one of bzr's (formerly Bazaar's) lead developers on why bzr failed and lost to git.[1] In his view, much of the blame rested on the decision to defer optimization until the product was more mature. But by the time it was mature, key architectural decisions were made that were hard to change. Here's a salient quote: "Premature optimization" is a dangerous concept. It tends to imply you can defer all consideration of performance until you…

People seem to always talk in absolutes, black and whites, concerning this topic. In my experience most engineers take a situational approach. Sometimes it is worth it to optimize early, sometimes it is not. Some things are worth optimizing, some not. Also some things are worth optimizing to certain level. These types of articles and claims conjure up a debate because everyone is imagining a different scenario in their heads. It is entirely plausible that each claim could be the…

Rich Hickey has a succinct quote that reveals the abuse that Hoare's "premature optimization" quote has undergone: the cheapest place to fix bugs is in design. And if we're going to proceed by quotation, another one to consider is Linus Torvalds': Bad programmers worry about the code. Good programmers worry about data structures and their relationships. IMHO, a big thing for junior programmers to unlearn is that one should begin by putting a sloppy version of the program in production…

Maybe it's because I've been working with computers for so many years, but as I was reading this paper I was thinking of all the exceptions to the points that it was making. I've seen too much time spent optimizing a product that was destined to never find a market, and too little time spent optimizing a product whose poor performance doomed its market entry. And, having spent literally months dedicated to optimizing code, I've also seen that some code…