JSFiddle - React, Tailwind, and code Playground

HTML

<script>
function singleVar() {
    var one,
		    two,
				three,
				four,
				five,
				six,
				seven,
				eight,
				nine,
				ten;
}

function multiVars() {
    var one;
		var two;
		var three;
		var four;
		var five;
		var six;
		var seven;
		var eight;
		var nine;
		var ten;
}

function millionInvocations() {
    var singleVarTime = 0,
        multiVarsTime = 0,
  		  singleVarStart,
  		  multiVarsStart;
	
	  for (var i=0, n=100000; i++<n;) {
		    singleVarStart = (new Date()).getTime();
				singleVar();
				singleVarTime += (new Date()).getTime() - singleVarStart;
				
		    multiVarsStart = (new Date()).getTime();
				multiVars();
				multiVarsTime += (new Date()).getTime() - singleVarStart;				
		}
		
		return {
		    singleVar: singleVarTime,
				multiVars: multiVarsTime
		};
}

function reportMillionInvocations(numInvoke) {
    var resultsDiv = document.getElementById('results'),
		    time,
		    divHtml = '<table border="1"><tr><th>Single Var</th><th>Multi Vars</th></tr>';
		
		document.getElementById('navUserAgent').innerHTML = (navigator.userAgent);
		
		for (var i=0; i++<numInvoke;) {
        time = millionInvocations();
		    divHtml += ['<tr><td>', time.singleVar, '</td><td>', time.multiVars, '</td></tr>'].join('');
		}
				
		resultsDiv.innerHTML = divHtml + '</table>';	
}
</script>
</head>
<body onload="reportMillionInvocations(10)">
<div id="navUserAgent"></div>
<div>Milliseconds Per Million Invocations:</div>
<div id="results"></div>