Slow loading of groups/tasks when many users are simultaneously connected

[kapil1garg]

During Delta Pairing today the pool needed to be reset multiple times, resulting in a long loading time for the group's tasks.

[kapil1garg]

this is hot-fixed for now through #59 , but we need a better solution for caching/retrieving popular tasks that doesn't involve subscriptions on the client.

in addition, it would be good to do a pass over all the subscriptions Pair Research is using and pare down the ones that can be 1-time calls instead