sooo yeah I just finally set up a test trying to publish 1000 ipns in parallel and well, they seem to be executing by IPFS in series regardless. The more answers my code says its waiting on, the longer it takes to get them all. Avg seems about 45sec per publish lol. Brutal.
But I have the option of having the server just publish one IPNS entry linking to a fresh list of profileId-to-profileTipCid for all authorized clients. This publish can run in a loop and take 60-90 sec each time. The internal caching can keep connected clients up to date on other clients freshest cid, and the big IPNS-published list can keep clients of remote servers no more than a few minutes out of date for the feeds of folks publishing through this server.