Using multi user controls in the same page best practice

[FB]

I am working on a resource management system,in a page i have a menu on left for the available resources,when a user selects one of the resources to modify,a user control related to that resource appears.I use the visibility property to show and hide the required user control.But there is a user control that is reused within most of the other user controls,on every post back that control fills its controls (drop down lists) with all the data for several times (the number of the user controls reusing it),this effects the performance as it loads all the data the show one user control and hide the rest. So in my case i make like 5 extra useless round trips within a single post back.I tried to load the user controls dynamically but that caused me other problems in the partial post backs and the state of the user control.Any idea on the best practices for that scenario?