CloudFlare will proxy whatever site you configure, even if it is static.
Static websites will get the best speed boost from locally served assets (much reduced latency from the local POP) because the page itself can be cached (presuming headers on origin site are correctly set). Especially for page requests from international users.
Sorry, I wasn't clear. What I meant was that since HN is dynamic its dynamic content is not usually cached. I mentioned specifically "dynamic" sites on my parent comment because as of this month Cloudflare can host static pages.
Static websites will get the best speed boost from locally served assets (much reduced latency from the local POP) because the page itself can be cached (presuming headers on origin site are correctly set). Especially for page requests from international users.