EDIT

If you have not done yet can you also please verify that the menu creation will never create a service call? I first thought so but then closed the details view and the supplemental data view and no call was send anymore. Unfortunately I could not debug in my IDE as it is broken.

But it looks like the only critical code part is getElementCounts() which loads the description elements. But as they are loaded during fact view loading already this should not result in a service call, correct?

However, during the first usage with open details/suppl.data view I had to wait relatively long for the menu. I guess the reason is that both the views are first loaded before the menu is created. Is there any possibility to change this order? Usually a context menu call even does not expect a xx views loading at all. Is it possible to show the menu without setting the focus and loading the views? Ofcourse also this is a another ticket and not covered by this ticket.

A final issue I found. Even when clicking a second time on a fact view tree item I observed at least 1 service call (I tested in rem_conf_am/Testklass/Test me factual data) when clicking on either the Fact Dataset or some single facts (but not on the feature node). This happens only with open details view, so it is caused by the det view. Can you check if these calls are really necessary? Also here it might be a new ticket.

Can you still move the "max per dataset" in details view deeper. Below the Available for information and above "Max states". And can you still rename "Max per dataset" to "Max n per dataset" and "Max states" to "Max n states"? This is maybe easier to understand.

For another minor open issue see #10332#note-12