i'd love to know the operations they were doing and what they used the sorted sets for. I find for this type of thing, if the ids of the users are integers you

i'd love to know the operations they were doing and what they used the sorted sets for. I find for this type of thing, if the ids of the users are integers you can often use a bitset and optimise the crap out of it via SIMD. If memory is a huge concern, or if the data is super sparse you can use a roaring bitset.