record vs map

speed_test.clj

(defrecord Simple [value])

(deftype Basic [value])

(with-out-str
  (time
   (dotimes [i 100000000]
     (set! (Basic. i) :value (* 2 i)))))

(with-out-str
  (time
   (dotimes [i 100000000]
     (assoc (Simple. i) :value (* 2 i)))))
"\"Elapsed time: 1479.908383 msecs\"\n"

(with-out-str
  (time
   (dotimes [i 100000000]
     (assoc {:value i} :value (* 2 i)))))
"\"Elapsed time: 3889.025598 msecs\"\n"