I use a blog that does three 'direct' (do you mean synchronous?) database queries for every pageview. Language was PHP5 (I feel like 7 got a lot faster but didn't do benchmarks so idk). Standard WAMP stack, renders in about 35 milliseconds on 2001 (sic) hardware iirc, and the HN homepage is very comfortably under 10 requests per second, so it's idling most of the time.

Database queries and interpreted languages aren't an issue at all. You need to be majorly unprepared to not be able to handle HN load. What I think people might overlook is that there will be other news outlets and social media that link to their website also. So it's hard to pass a verdict, though someone mentioned it's WordPress in a sibling comment so... I'd put my money on that it's poorly optimised but we can't really know I guess