In my experience, appcache only improves second loading time. You need all of these other techniques to improve first loading time. 2nd time is much, much less important to optimize, because returning users have already gotten through the annoyance filter, know what they are in for, has at least subconsciously accepted the necessity of the load time they experienced the first time. It's nice they won't have to experience it a second time, but if first-time loading is very long, your second-time users are going to be much fewer.
I had written quite a bit here on the sorts of things that I do to make very short time-to-first-view sites, but basically the techniques all fall in place if you setup Google Analytics and use their Page Speed Suggestions. You should be able to get to 95% on mobile, 98% on desktop (I lose points on some 3rd party scripts I've included for order processing, so I can't get around it.). It will be a bit difficult your first time, but after that you will know what all the tricks are and future sites you will just make "right" the first time.
AppCache is client-side; it caches a certain set of URLs in your browser so that they are available with no HTTP request. It doesn't work until your browser has hit the page once, downloaded the cache manifest, and saved the files.
Loading more than just the first page the user visits quickly is still really important though. If each link the user visits is slow they're more likely to leave the site and that reduces your chance of a conversion.
I had written quite a bit here on the sorts of things that I do to make very short time-to-first-view sites, but basically the techniques all fall in place if you setup Google Analytics and use their Page Speed Suggestions. You should be able to get to 95% on mobile, 98% on desktop (I lose points on some 3rd party scripts I've included for order processing, so I can't get around it.). It will be a bit difficult your first time, but after that you will know what all the tricks are and future sites you will just make "right" the first time.