The lesson is: Even if you know exactly what is going on in you system, measure performance, don't speculate. You'll learn something, and nine times out of ten, it won't be that you were right!!
Code never lies, comments sometimes do.
Simple, not easy. There's a difference.
The wages of sin is debugging.
If there's only one answer, then this must not be a very interesting topic.
When we use a language, we should commit ourselves to knowing it, being able to read it, and writing it idiomatically.