Performance testing

perf-testing.el

(defconst json-string
    (with-temp-buffer
    (insert-file-contents-literally "/home/kyoncho/Public/Desktop/large.json")
    (buffer-string)))

(progn
  (setq my/call-counter 0)

  (defun my/test-query-function (&rest args)
    (incf my/call-counter)
    t)

  (add-hook 'kill-buffer-query-functions #'my/test-query-function)

  (json-parse-string json-string)
  my/call-counter) ;; => 32982