Slow cljs loops

force-realized.clj

(ns cljs-test.client)

(defn now []
  (. (js/Date.) (getTime)))

(let [nums (doall (range 0 1000000))
      start (now)]
  (doseq [n nums]
    )
  (. js/console (log (- (now) start))))
;;4500-6500ms

(js* "var c = 0, start = cljs_test.client.now(); for(var i = 0; i < 1000000; i++) { c += i; }; console.log(cljs_test.client.now() - start);")
;;15-30ms

loop.clj

(ns cljs-test.client)

(defn now []
  (. (js/Date.) (getTime)))

(let [start (now)]
  (doseq [n (range 0 1000000)]
    )
  (. js/console (log (- (now) start))))
;;4500-6500ms

(js* "var c = 0, start = cljs_test.client.now(); for(var i = 0; i < 1000000; i++) { c += i; }; console.log(cljs_test.client.now() - start);")
;;15-30ms

loopRecur.clj

(ns cljs-test.client)

(defn now []
  (. (js/Date.) (getTime)))

(let [nums (doall (range 0 1000000))
      start (now)]
  (loop [n nums]
    (when n
      (recur (next n))))
  (. js/console (log (- (now) start))))

;; Advanced mode output:
;;for(var sc = oc.call(f, mc.call(f, 0, 1E6)), tc = rc.call(f), uc = sc;;) {
;;  if(s(uc)) {
;;    uc = J.call(f, uc)
;;  }else {
;;    break
;;  }
;;}
;; Advanced mode time: 1700-2000ms

(js* "var c = 0, start = cljs_test.client.now(); for(var i = 0; i < 1000000; i++) { c += i; }; console.log(cljs_test.client.now() - start);")
;;15-30ms

loopRecurNoSeq.clj

(ns cljs-test.client)

(defn now []
  (. (js/Date.) (getTime)))

(let [start (now)]
  (loop [n 0]
    (when (< n 1000000)
      (recur (inc n))))
  (. js/console (log (- (now) start))))
;;120ms

(js* "var c = 0, start = cljs_test.client.now(); for(var i = 0; i < 1000000; i++) { c += i; }; console.log(cljs_test.client.now() - start);")
;;15-30ms