I have 2 classes that implement the same interface,A Client And a Spouse Both implement IClientBase,but client actually implements IClient(which extends IClientBase a little bit further),Spouse only inherits from IClientBase. A client class,contains a spouse. I have built a few usercontrols and used databinding so i can bind the client object to them and edit it. my biggest usercontrol(that has a few user controls in it) is called MainClientcontrol and is expecting an IClientBase object as its datasource. I have put 2 of these on a form,that is bound to an IClient instance,and binded one to the Client itself and one to its spouse,all properties DataSourceUpdateMode is OnPropertyChanged While the control thats bound to the client itself is responsive,the one that is bound to the spouse is very slow. Unless I change all or most of the bindings update mode to OnValidation - a thing I do not want to do. I hope i made myself clear, Any help will be appriciated. :)