Web Forms :: Dynamically Loading User Controls In Tabs In Page?

I am using ASP.Net 2.0 with Ajax.

I am working on a pretty heavy page in an application and the scenario is:

There is a Tab control in the page, having four tabs. These tabs individually consist of different user controls and other asp controls. Most of these usercontrols in turn consist of other user controls. Every user control contains huge javaScript functions which validate them, populate controls and call web services.

What I am trying to achieve is to load only the Tab and its user controls on the page load and when the user clicks on a specific tab, load its contents (User controls) dynamically. Once that is done, I am setting the tab's postback to false to prevent loading it again once loaded.

I tried to achieve this by making the user controls in the other tabs - visible="false" in the markup and loading them from server side on some specific event. But that causes the javaScript functions in those user controls to give errors ('Object expected') when I go to that tab.

If I set the user controls in the other tabs to visible true, then no matter what; the page life cycle goes to each registered control and loads every subsequent control in that web user control which makes the main page slow (on loading and every postback).

The position of the Tab and the inner user controls is fixed. Although I am taking care that no data is populated unnecessarily on the page and user controls on hidden tabs, I dont want the tabs to get loaded altogether unless requested. If I load them on runtime, their corresponding javaScripts start giving errors.. note that I am not generating the controls on runtime, they exist in the page design. I just dont want to load them dynamically