bbPress.org

@danblumenfeld, seems like that would work fine for small sites with a limited number of users and topics, but what about when you get into the thousands of users with thousands of topics? At that point you are saving an extremely long meta key for every user. I would worry about scalability, although I think that’s true of any attempt at solving this problem.

As for pagination with jumping to the first unread reply, it might be more practical to simply give the user a “jump to last read reply” button using bbp_get_reply_permalink( $reply_id );