Collect key performance metrics, dump in document then reload page for another run.

perf-coll.js

(function () {
	"use strict";
	var t = performance.timing, 
		t1 = t.navigationStart,
		arr = [t.responseEnd - t1, t.domContentLoadedEventStart - t1, t.loadEventEnd - t1],
		storage = sessionStorage,
		storageKey = "perf-coll",		
		coll = JSON.parse(storage.getItem(storageKey) || "[]"),
		serialized;
	coll.push(arr);
	serialized = JSON.stringify(coll)
	storage.setItem(storageKey, serialized);
	document.body.textContent = serialized;
	console.info(coll.length);
	setTimeout(function () {
		location.reload();
	}, 2000);
}());