(import chicken scheme)

(define (fu x)
  (fx+ x 1))

(define (fu2 x #!optional y)
  (fx+ x 1))

(define x 0)

(time
 (let loop ((i 0))
   (set! x (fu i))
   (when (fx< i 10000000)
     (loop (fx+ i 1)))))

(time
 (let loop ((i 0))
   (set! x (fu2 i))
   (when (fx< i 10000000)
     (loop (fx+ i 1)))))