One of the main features of HTTP/2.0 is the Server Push. When it is available, that means, being supported by the protocol, the server, and the browser client—it lets the server send ("push") data to the client before it asks for it.
It is one of the most wanted features in JSF 2.3 and probably the one that demands less effort to use if your application is based on JSF—just migrate to a Java EE 8 compatible server and then you are done.
This recipe will show you how to use it in your application and will even let you compare the performance between HTTP/1.0 and HTTP/2.0 in the same scenario.