The client will need to block until the subscription is created... Are you doing this on a single application?
Maybe you should pre-create that through management on the server?
Can you try 2.3.0 on this?
It's a termin-view-module in a framework. And if you switch to another day, it creates subscriptions (~60) and removes old one. It would be difficuld to redesign this module.
What you mean with pre-create?
Its not easy to test with new version, but we can try it. Are there made some changes (performance) in creating subscriptions in the new version?