increase feed storage
Old feed data should minimum be kept for 30 days and 1000 items.
Preferably it should be kept for infinity (maybe only limit unread count).
This is especially important for reading webcomic backlogs.
As you are not storing any rich media there really should be room for improvement in this area.
Duplicate. Please vote for http://bazqux.uservoice.com/forums/190752-general/suggestions/4140770-expand-500-entry-limit