Well, i´m impressed with this plugin, that´s awesome!! :)
The first thing that happens, is that you have a website, then, you realize that your website must be fast to provide a good experience to your visitor. So you go to pagespeed and get some advices to improve the functions.
Cache / Cache Web Browser / Images / Minify JS and CSS / Gzip / Deferredfunctions.js / ASYNC JS AND CSS.
I think one of the most important things: ASYNC JS AND CSS.
Your website must fast, visitors don´t like and don´t have time to slow things... So, the content must be first, JS and CSS load asynchronous, and make the show happen!
Every website, must have a different experience with this plugin, at my theme, some adjusts were need, and now that´s working NICE ! :)
It gives you the chance to put some very important files at an exception list, which is very good to separate things and do a better administration of loading settings.
And i want to thank the plugin´s author, that is a very helpfull person, and he look like to be in a mission to improve more and more this wonderful work!
Thanks and Regards,