Feature to load/reload/lazy-load viewfield display

Problem/Motivation

I am using viewfields intensively. I also have a large number of entity types.
Some viewfields are organized in tabs (from the https://www.drupal.org/project/field_group → module).
These viewfields show large tables.

Loading an entity with many viewfields takes time. So (while Drupal is fantastically fast!) for even more complex uses cases it would be great to:

have an option when to load the viewfield content.
e.g.

1. load always (like it works now)
2. load on click of a button
3. load when tab (or containing element) gets displayed in browser
4. load after X (e.g. 5 seconds)
5. load in the background, when the rest of the page is done

Also in cases 2-5 a refresh button would be fantastic. So one can only reload one viewfield and not the entire entity/page ...

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes