Try it to see how your website does. It’s a google tool to gauge the performance of your website. Now, does anyone have a score above 20? What have you done to maximize your app/website’s performance?
I posted a reply to another thread where I explained how I improved loading times on my large single page app.
Also, I’m not sure if anyone has tested it, but I suspect the new responsive engine will have better load times, especially once it is out of beta and optimization has been done with it.