It helps improve you programming by catching spelling errors and little sloppy bits of code... there is no efficiency boost, and in fact, it's not a bad practice to comment out warnings and strict in production code. (at least that is my impression, tho I don't think it makes a huge efficiency boost)

It is an excellent way to keep you from making some common mistakes, though... and that is worth a lot right there.

                - Ant
                - Some of my best work - Fish Dinner