@FlatBox: Are you using a 64 bit version of windows and making sure you are not opening a lot of XAML windows, as I only have speed issues on old 32 bit machines?

I would recommend you use MVVM, binding to commands and not to properties. Silverlight 5 introduced XAML debugging, which is sure to be included in the net version of WPF. I use Resharper that identifies 90% of my XAML issues so I reiterate "It's a case of bad workmen blaming their tools"