In perfectly readable code, it's easy to notice performance problems. In my experience, unreadable code is usually where the worst performance problems are, be

In perfectly readable code, it's easy to notice performance problems. In my experience, unreadable code is usually where the worst performance problems are, because that's where they are the hardest to find and fix. You seem to be conflating readability with formatting, which is not what I mean by readability. Poor and inconsistent formatting adds some friction to reading, but it's a relatively minor part of readability.