Sure. Everyone remembers from Algorithms 101 that a constant multiple ("a thousand times slower") is irrelevant. What matters is the scalability. Something that

Sure. Everyone remembers from Algorithms 101 that a constant multiple ("a thousand times slower") is irrelevant. What matters is the scalability. Something that's O(n) will always scale better than something that O(n^2), even if the thing that's O(n) has 1000x overhead per unit. But that's just a small piece of the puzzle. I agree that the user only cares about what the product does and not how the product works, but the what is always related to how, even if that relationship is imperceptible to the user. A product with terrible code quality will have more frequent and longer outages (because debugging is harder), and it will take longer for new features to be added (because adding things is harder). The user will care about these things.