If you use the popular Mozilla Firefox browser, here is good news for you: there is a new feature in the browser, Performance Monitor. It has appeared in Firefox 40, which is in the Nightly state as of this writing. Let's learn more about this new feature.
If you enter about:about in the address bar of Firefox 40, you will notice a new line which says the following:
Tip #1: see the full list of about: commands in Firefox
Tip #2: If you are using Firefox Nightly, it is good idea to check the about:about page from time to time to discover new and useful stuff.
Let's execute it. You can click the link in the about:about page or just type about:performance into the address bar of Firefox.
The following tab will be opened: