I'm not sure if I totally understand your question - but if a control's visible  state is set to false, it isn't rendered, and the code  contained in it shouldn't fire (no practical experience with this - just remembering something I read). If I'm wrong with this, would placing the user  control in a panel and setting the panel to visible=false work?

Get that code  out of Page_Load

Have it live in a sub or method.

Have the visible  property set invoke the method or the page.

Look at:
www.learnasp.com/.../sourcecode-searcheruc.aspx

specifically:
dbgrid.ascx

The database population code could not live in Page_Load because it would fire before the button event that gave it correct SQL. So that code lives in a sub called DataBind() although it could have been called GoGetdata() or whatever...

This will enhance performance greatly on my page + prevent  errors because variables could be null when the control is invisible  (not yet in scope).