Favor: could someone share an intelligent (or at least in-depth) write-up of the pros/cons of infinite scrolling? Most of what I'm finding on the web is content farmy.
Also: at what point is memory usage worth worrying about? Scrolling for pages on end has to be tough on a browser.
Most sites that implement infinite scrolling effectively "unload" content that's far enough off the screen, much like they delay-load content that's below your scroll area. The net memory usage shouldn't be dramatically worse.
Another possible pro (from the site-owner's perspective) is increased user engagement. When you are quietly loading more content all the time, it's easier for the user to continue to say, "I'll just look at one more post."
On the cons side, as others have mentioned, if you navigate away from an infinitely scrolling page, then click the back button, you often don't land in the correct place.
Well, maybe; mobile browsers are often more constrained in terms of RAM. My Android phone only has 256MB, so infinite scrolling tends to cause the browser to bail out.
Also: at what point is memory usage worth worrying about? Scrolling for pages on end has to be tough on a browser.