NIPS needed:

1) "select: ['id']" filter so you only get matching event ids and not the full event 10 times. You can then ask only 1 node for the full event, or skip if you already have it.

2) Bloom filter for "I already have these events, don't send them". Can be resource intensive on the relay side and not usable in all queries.

3) Follow distance filter for authors, so you don't get irrelevant spam. Iris discards stuff from unknown authors on the client side, but would be better if they weren't sent and processed in the first place. Shouldn't be difficult to implement with some SQL wizardry.