Freetextbox may not currently work inside an updatepanel, but at least it works inside the new tabcontainer/tabpanel in the Ajax Control Toolkit.  So, rather than wait for all your FTB's to render, you can at least make the page more organized by putting them in their own tabs. 

Oh, and by the way, for all you other Ajax Control Toolkit fans out there:

TabContainer cannot have children of type 'System.Web.UI.WebControls.Repeater'.

Apparently you can't dynamically create tabs inside of a tab container.  At least not this way.   Pity.