and unless that matters.

I originally wrote O(n^4) vs. O(n^2), which is something that actually happened to me two days ago, but thought I'd go more basic. I should've gone real-world example.

But yes, O(n^2) vs. O(n) can matter for large n.

I don't disagree though. Even though in much of my work performance is usually not a concern, I still run into plenty of situations where it really is. But I run into more situations where I probably spend more time optimizing when I don't need to. YMMV, obviously.

I'm forced to optimize unnecessarily in code reviews at work. Gotta save that extra microsecond when the user pushes that button!

Ha, I spend a decent amount of time trying to explain to clients how it's worth their while to decrease a page's load time from 20+ seconds to < 5 in just a few hours of work...

I'd feel much more job satisfaction from that.

it's web development and it pays well enough...