Make panel rendering lazy

[stevan]

The panels are rendered immediately upon fetching of data, which is fine if you actually look at the panels, but is a waste if you never open them. The ideal situation is that we extract the minimum relevant data to render as much of the panel as we show.

This is particularly bad when fetching AJAX sub-requests as each AJAX call will kick off a data fetch from the server and then a bunch of rendering of panels.