Emacs Lisp alist vs. hash

alist-benchmark.el

(require 'cl)

(defun test-alis-1 (i n)
  (let* ((alis (loop for i from 0 to 10 collect (list i)))
         (start (float-time)))
    (dotimes (_ n)
      (assq i alis))
    (- (float-time)
       start)))

;; The above is somewhat unrealistic, though. You usually want the              
;; value, not the pair, so the cdr is almost always present.                    
(defun test-alis-2 (i n)
  (let* ((alis (loop for i from 0 to 10 collect (list i)))
         (start (float-time)))
    (dotimes (_ n)
      (cdr (assq i alis)))
    (- (float-time)
       start)))

(defun test-hash (i n)
  (let* ((hash (make-hash-table :test 'equal))
         start)
    (loop for i from 0 to 10 do (puthash i nil hash))
    (setq start (float-time))
    (dotimes (_ n)
      (gethash i hash))
    (- (float-time)
       start)))

(message "alis-1: %.3f" (test-alis-1 0 100000000))
(message "alis-2: %.3f" (test-alis-2 0 100000000))
(message "hash..: %.3f" (test-hash 0 100000000))