I am creating an enterprise web template to be used for development of all our web applications. Many of our existing applications take a while to load because of the amount of
Definitely #2. Adding an UpdatePanel
is a whole can of worms, and if you're not using them already on a given page, adds a lot of overhead.
The code involved in using jQuery to do this is trivial. There's a nice little plugin called blockui that can be used to render an effect and disable all controls on an area. It's not too hard to do this without the plugin either, but why reinvent?