"'Premature optimization is the root of all evil' is the root of evil"
https://medium.com/@okaleniuk/premature-optimization-is-the-...
http://ubiquity.acm.org/article.cfm?id=1513451
http://www.joshbarczak.com/blog/?p=580
http://scottdorman.github.io/2009/08/28/premature-optimizati...
It's basically an excuse to not think about the performance or implementation of your entire product until the end and then, when you use a profiler and chop away "10%" here and "20%" there, you still end up with a slow-as-piss program with every function taking less than 1% total time. Then what do you do?
Oh yeah, what you should have done in the first place. _Think_ about how your program actually functions so you can remove all of the insane systemic, architecture decisions you made that all bleed a fixed amount of time every single function call. That's the difference between an engineer, and script kid. If you're not reasoning about _the entire platform_ (all the way down to the cache lines), you're not engineering. You can abstract all you want, but those abstractions don't magically prevent the underlying hardware and architectural decisions from affecting the product. Abstractions tools (read: approximations!) for high-level reasoning. They're not magic "you don't have to think [about low level implementation]" spells.
Actual experts keep trying to warn you guys about abusing that quote, but nobody apparently ever listens. Stop quoting it like a bible verse, because just like bible verses, everyone forgets the entire context and just uses it like a bloody bumper-sticker slogan.
In the words of Saul Williams: "You have wandered too far from the original source, and are emitting a lesser signal."
The full Donald Knuth quote:
>The real problem is that programmers have spent far too much time worrying about efficiency in the wrong places and at the wrong times; premature optimization is the root of all evil (or at least most of it) in programming.
That quote sounds much less like a law handed down by God, and more a guideline from experience, no?
Optimizing the wrong things (things that get thrown away when you change your program as you work toward your goal) ends up wasting time. But just because that was applicable _in the 70's_ doesn't mean modern programmers have the same mentality of "optimize optimize optimize." Modern programmers have the opposite. They're so afraid of having to learn how cachelines work, they use that quote to prevent having to do any optimization (or understanding of architectural layout tradeoffs). I can't count how many programmers I've met that hear "cache" and their eyes glaze over like it's some magical, incalculable thing.
Watch a lecture from Mike Acton, where on consoles, they don't have the luxury of writing poorly written, un-optimized code. They _do_ have to understand the entire platform to ship a competitive title. Because any optimizations they do, for a fixed platform, means they can pump out a better experience with those extra CPU cycles. An experience that elevates them above their competitors.
https://www.youtube.com/watch?v=rX0ItVEVjHc