@nomis5 Most of the advice has been floating around online articles for quite a while. Much of that we incorporate into our client's sites and it works very well. The "less than one second" thing is very achievable but it depends on your site. ymmv.
@jojy I'm at a client site right now and can't really write about this but you can't take a desktop site and always expect to serve it to mobile and be happy. Mobile != desktop and things must be cut out or otherwise served at another time. If you must have a heavy site deliver the same content to mobile, you're doing it wrong and not doing your visitor any favors.