I think this will make a big difference. Relays could then subscribe to this aggregation service for counts and then embed those counts into the events as they serve them as suggested by tmathews on github, and that way most clients wouldn't have to make additional queries.
Discussion
That's the goal, at least unless/until Nostr incorporates some form of aggregation for this info. Besides, for things like Likes, querying one relay isn't enough since people write to different relay sets. I'm aggregating data from all the top relays (currently 27 of them) so the reaction counts and follower counts etc should be pretty accurate. Nostrum is running on a high end production web server tied to a high end production database server, so it can handle quite a bit of load.