If you look at Firefox memory consumption while browsing Twitter, you'll see the main culprit is, like always, DOM operations (repaint/reflow particularly). Solution: use Chrom{e|ium}.
Obvious difference: I expect not to get my HDD corrupted because I visited an arbitrary website, I understand it might be the case if I download AND run an arbitrary program.
It's OK while it is sensible (after all, you will inform your friends you have published a new blog post or whatever) and not some heavy "please upvote" campaign.
You read my mind for "parity of a set". So Q.E.D.: parity is only applicable to reason about numbers (and infinity is not a number). See also surreal numbers.
A friend of mine opened a company (EURL) in 2 weeks and for about 300 euros. Honest. It'd be twice as expensive in, say, Estonia (I run a business there).
Reverse-proxying via nginx would solve this problem and more: the arbitrary 30 second limit on form submission (hotspots sometimes are slow...), nginx could handle rate limiting & logging instead of srv.arc, etc. The Arc codebase would btw be smaller and cleaner (no policy/sanitization code, etc.).
Serving static content via Apache was a first step ;-)