optimize scrolling on emacs

scroll.el

(setq scruptime 0)
(global-set-key [mouse-4]
 '(lambda ()
  (interactive)
  (setq scruptime_new (float-time) )
  (setq scrup_dt (- scruptime_new scruptime))
  (if (> scrup_dt 0.05)
   (scroll-down-line 1)
  (scroll-down-line (ceiling (/ 0.05 scrup_dt) ) )
  )
  ;(message (number-to-string (ceiling (/ 1 scrup_dt) ) ) 
  ;(previous-line (ceiling (/ 0.01 scrup_dt) ) )
  (setq scruptime scruptime_new)
  ;(recenter)
  )
  ;'(lambda () (interactive) (previous-line 1) (recenter) )
 )

(setq scrdntime 0)
(global-set-key [mouse-5]
 '(lambda ()
  (interactive)
  (setq scrdntime_new (float-time) )
  (setq scrdn_dt (- scrdntime_new scrdntime))
  (if (> scrdn_dt 0.05)
   (scroll-up-line 1)
  (scroll-up-line (ceiling (/ 0.05 scrdn_dt) ) )
  )
  ;(message (number-to-string (ceiling (/ 1 scrup_dt) ) ) 
  ;(previous-line (ceiling (/ 0.01 scrup_dt) ) )
  (setq scrdntime scrdntime_new)
  ;(recenter)
  )
  ;'(lambda () (interactive) (previous-line 1) (recenter) )
 )