Testing React vs Reagent update latency

reagent-latency.cljs

(def start (atom nil))

(def log (atom []))

(defn latency-test []
  (let [a (r/atom 0)]
    (fn []
      (let [[b update-b] (react/useState 0)]
        (react/useEffect
          (fn []
            (let [now (js/performance.now)
                  d  (- now @start)]
              (swap! log (fn [log]
                           (let [log (conj log d)]
                             (if (>= (count log) 100)
                               (do
                                 (js/console.log (str/join "\n" log))
                                 [])
                               log)))))
            js/undefined))
        [:div
         [:button
          {:type "button"
           :on-click (fn [e]
                       (reset! start (js/performance.now))
                       (swap! a inc))}
          "ratom"]
         [:button
          {:type "button"
           :on-click (fn [e]
                       (reset! start (js/performance.now))
                       (update-b inc))}
          "hook"]
         b
         @a]))))