Some stats from my front-page a month ago:
- Time on front page: 15 min
- Views in first 15 min: ~5000
- Views in first 60 min: ~7000
- Views in first 600 min: ~11,000
- Views over the next 5 days: ~5000
HN front pages bring a bunch of users quickly, but it isn't a scale that will cripple moderate hardware with some basic performance tuning (directly serving assets, for example). The tail is also great, fully 3/4 of my post-front-page views come from click-throughs on social.