Custom events and the live hit feed.
The feed polls every 10 seconds while the page is open — it's the one view
where "what's happening right now" is the point, and one indexed
ORDER BY inserted_at DESC LIMIT 50 is cheap enough to repeat. Everything
displayed is already non-identifying, so there is nothing to redact: the
visitor column shows the first characters of the daily hash purely so you can
see two hits belonging to one person.