Not sure if this is right place but has severe asyncio blocking problems. It can take upwards of 30s to download 4kb worth of data. I haven't really looked into the issue but it seems that this is happening because although Tornado *is* async, and the routes are coroutines, everything else is sync (including the calls to the database).
interesting, can you get an example of this? we've just migrated the database to a new method of database access so would be good to verify that's not related