(* いつもの *)
let rec map1 f = function
　　[] -> []
　| x :: xs -> (f x) :: (map1 f xs)
;;

(* CPS 変換 *)
let map2 f lst =
　let rec map2_sub k f = function
　　　[] -> k []
　　| x :: xs ->
　　　let t = f x in
　　　map2_sub (fun y -> t :: y) f xs
　in
　map2_sub (fun x -> x) f lst
;;

(* adhoc tail-call *)
let map3 f lst =
　let rec map3_sub f result = function
　　　[] -> result
　　| x :: xs -> map3_sub f ((f x) :: result) xs
　in
　map3_sub f [] (List.rev lst)
;;

どれが早いでしょう。