Doesn't HN run on a single computer under some desk? I heard this one time but never verified. Maybe it's time for a proper cloud deployment?
I'd be curious to peek at HN Source code. I recall there was a version posted online but it's several years old.
The most recent change I remember was when Twitter and GitHub posts were split based on the user the link belonged to (i.e. GitHub.com/dang is different than github.com/torvalds now).