If the top-line goal is to make the page as responsive as possible, I'm a little stumped as to what the alternative would be beyond delaying the loading of arbi

If the top-line goal is to make the page as responsive as possible, I'm a little stumped as to what the alternative would be beyond delaying the loading of arbitrary html and JS. Can you think of a way to load arbitrary HTML immediately and not cause any page responsiveness issues on, say, a three year old Android device?