>>2 It's annoying on a slow internet connection because it reloads everything, not just the recent posts.
That said, I'm not sure an update button is possible here. Pretty sure this site doesn't use a database, just re-creates the entire page with the latest posts added, so there's no way to check for new posts except to read the latest version of the page.
That process will ultimately load just as much content (minus images) unless done purely on the server-side of things.