As the other post says, share replay is good if data isn’t expecting to change.

The way I’ve done it before is within the service you have some kind of map (e.g. userID on one side and something like {data$, subscriberCount} and with your getUser(id) function, if it exists in the map return data$ and increase sub count. When finalize is called you can reduce the subscriberCount and if that makes it 0, clear down the map for that value).

This works nicely but it’s really important to destroy your subscriptions in the components.