My primary site not only stores articles in the DB, but runs them through an extended, custom markdown parser upon retrieval, and processes and reports event data on every page load. It was still successfully returning ~250 reqs/sec before I'd bothered implementing any caching or pre-compilation of markdown at all.
In contrast, people recently HNed are reporting about 12-15k visits over a day. That's something a single server on a $5/month VPS can handle in a minute
This matches my experience. I think I got about 10k visits over the course of a day, 80% within the first three hours.