Hi, Spyridon.
shouldn’t the response time for pub/sub stay low based on the redis server
That’s not exactly true! If your DB is not ok, redis-oplog won’t do much. On every change event, redis-oplog fetches a full copy of the changed document before propagating the changes. If your db is slow, this will be slow too!
On the other hand, if you saw degradation without changes in your code or changes in the audience, there is a big chance it’s in your DB.