>An interesting and counter-intuitive consequence of Theorem 1, derived in Section 7, is that the fastest program that computes a certain function is also among the shortest programs that provably computes this function. Looking for larger programs saves at most a finite number of computation steps, but cannot improve the time order.

Pretty cool paper, it's from 2002 that's amazing. I'm having trouble locating the factor of five explanation. Why 5? Is it just the safest lowest bound they could guarantee without too much prodding?