What is the page load testing service?

Question

Computer networks

Tell me, please, is there a site that I want to start optimizing for page loading, is there any service that would probably take measurements, namely, let's say, it loaded 10 times, and then gave out the average time?
After that, I would make some changes and again measure and show the differences, and, let's say, even indicate where the changes occurred in terms of download speed.

Answer 1

One - tools.pingdom.com/fpt/
Two - developers.google.com/speed/pagespeed/insights/
Three - Network tab in built-in browser plugins like Firebug
This is the bundle I use when optimizing. And nothing more is needed.

Answer 2

Download time can be viewed directly in the browser. In chrome, for example, F12 - Network
(as an option)