XWiki becomes unresponsive when viewing certain Panels on larger wikis

I reproduced this bug on a server with XWiki 5.4.5 and Statistics enabled.

When I visited the Space Administration - Panel Wizard page, a page with lots of Statistics-related panels, the server was unresponsive for a number of minutes.

This happens because the information from those panels is gathered and displayed in real time.

We could add a check for every Statistics-related panel: if the current page the panel is on is a Panel Wizard one, then we could just display the title of the panel or something similar.