Quotes in efficiency
Costs do not exist to be calculated. Costs exist to be reduced.
Premature optimization is the root of all evil (or at least most of it) in programming.
A woodsman was once asked, "What would you do if you had just five minutes to chop down a tree?" He answered, "I would spend the first two and a half minutes sharpening my axe."
There is nothing so useless as doing efficiently that which should not be done at all.