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by cedsav 6240 days ago
What if they have a fast way to get the intersect between followers of 2 different users? In this case, if a message is a @reply they could ignore the follower lists of each users and use the intersect list only (which can be cached). Supporting the 'get all replies' option means that they also need to consider the full follower lists and then deduplicate. .. just guessing here