lisp performace question: how efficent are (long) list parameters?

[leo <leo@bella.local>]

hi there

just a little thing for a lisp beginner. i have written a function:

(defun first-free-position (positions)
  "returns the first free position in POSITIONS of all frames"
  (if positions
      (let ((list-of-frames (frame-list)))
        (if (frame-on-position (car positions) list-of-frames)
            (first-free-position (cdr positions))
          (car positions)))))

this function recomputes `(frame-list)' for every recursion. so i
thought to set `(frame-list)' to a variable which could be carried
through as parameter:

(defun first-free-position (positions all-frames)
  "returns the first free position in POSITIONS of all-frames."
  (if positions      
        (if (frame-on-position (car positions) all-frames)
            (first-free-position (cdr positions) all-frames)
          (car positions))))

called like `(first-free-position position-alist (frame-list))' this
version computes (frame-list) only once, but the list `all-frames' is
put every time on the parameter stack.

so, what is more effiecent?

cheers, leo