JSFiddle - React, Tailwind, and code Playground

HTML

<div>timestamp: <span id="timer"></span> ms</div>
<div>resolution: <span id="res"></span> ms</div>

CSS

div {font-size:6em;}

JavaScript

var timeout = document.getElementById("timer");
var resout = document.getElementById("res");
var start = window.performance.now();
var count = 0;

setInterval(function(){ 
    var delta = window.performance.now() - start;
    ++ count;
    resout.innerHTML = delta / count;
    timeout.innerHTML = delta;
}, 0);