(defun range (from to)
  (let ((i to) (r nil))
    (while (>= i from) (setq r (cons i r)) (setq i (1- i)))
    r))

(defun sum (xs)
  (let ((r 0))
    (while xs
      (setq r (+ r (car xs)))
      (setq xs (cdr xs)))
    r))

(defun run ()
  (sum (range 0 100000)))

(defun bench ()
  (dotimes (i 1000)
    (run)))

;(bench)                                 ;12235ms => 12m each