optimizations that are not premature are a win though, and by making it standard to consider performance issues from the outset, you and tour team get better at it, such that it doesn’t cost time to default to pretty efficient solutions.
also some basic tech choices can often get you large constant factor wins without any downsides, like using a languages that are at least jitted rather than interpreted.
- "At the end there are a lot of changes all the time to functionality and implementation and optimizations early get wasted very quickly"
- "optimizations are opportunity losses at the beginning of a product"
The question is: which optimizations are premature and which aren't?
Cheap optimizations that are known to work (compiling in release mode, enabling HTTP cache in your web server, using a fast sorting algorithm on large arrays...) are good even if you don't need them right now.
Now if junior doesn't implement them, are they didn't do required optimization, or do they do premature optimization if they did?
And that, my friends, is a contradiction!
The preparations you made that turned out to make your life easier, the things you regret not doing, and the things that ended up being a total waste of time.