[groby_b]

If we had learned something, we'd have learned the FULL quote, wouldn't we?

"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil"

Note, "small" and "97%".

That means that you should make the right large-scale decisions before you code. Or measure.

[jasonwocky]

Yes. Another way to put this is that there's a difference between "designing to be sufficiently performant" and "optimization".

[groby_b]

It also means "don't be boneheaded about local performance". That's the other 3%. I wish it didn't need to be said, but there are quite a few projects I've seen where people blatantly ruined performance, all the while quoting Knuth.