Given the "more" links on the front page, I'm guessing HN is using continuations as state storage mechanisms, and that they're stored on a per-user basis. So, I

Given the "more" links on the front page, I'm guessing HN is using continuations as state storage mechanisms, and that they're stored on a per-user basis. So, I'd expect the site's RAM requirements to be pretty hefty just on that basis, hence the 12GB of RAM.