Recursion is stupid and wasteful

There is nothing that recursion can do that can't be done simpler and more elegantly with a plain for loop.

>>1
(defmemo fast-fib (x) (if (< x 2) x (+ (fib (- x 2)) (fib (- x 1)))))

;; definition of defmemo cut out for simplicity (though it isn't hard to write)