It is schedule every few hours. The biggest issue now is twitter limit request, which is what I'm solving right now.
Also the attention is not that bad (8775 visits so far). Also, heroku's varnish cache on static assets, html page and on Ajax requests is pretty great.
And mixpanel is handling the metrics, so I'm pretty covered.
How often does the list get refreshed? Or is it live? (if it's live, how are you handling the attention without melting servers)