Simple function benchmark comparison

timetest.clj

(defn time*
  [fs iterations]
  (map-indexed
    (fn [idx f]
      (let [t (with-out-str
                (time
                  (run! f (range iterations))))]
        {:idx  idx
         :f    f
         :time t}))
    fs))

(time* [(fn [_]
          (merge-with into
            {:omg {:lol 12
                   :wat {:wooo 12}}}))
        (fn [_]
          (merge-with merge
            {:omg {:lol 12
                   :wat {:wooo 12}}}))] 1e7)
;; => ({:idx 0,
;;      :f #function[dev/eval76792/fn--76793],
;;      :time "\"Elapsed time: 1751.630289 msecs\"\n"}
;;     {:idx 1,
;;      :f #function[dev/eval76792/fn--76795],
;;      :time "\"Elapsed time: 1173.778828 msecs\"\n"})