Some of those optimizations become irrelevant (or downright bad) with http2. Inlining CSS ans JS is no longer best practice when you can do a server push of those and avoid sending the extra bytes once the files have been cached by the browser.
Some optimizations can backfire. Adding async to the external JS is a great tip.. unless you have dependencies between your different scripts (i.e. you need one to be loaded before the other one gets executed)
Some optimizations can backfire. Adding async to the external JS is a great tip.. unless you have dependencies between your different scripts (i.e. you need one to be loaded before the other one gets executed)