"You know the problem, you are developing a WPF application and you want to see what your XAML looks like. Normally you have to compile, start, and see if everything looks like you want to. With FastWPF this process is getting speed up because it will show you instant the result within Visual Studio during your development. It is not trying to do the design work for you, but it specializes in showing you a preview of your XAML. A preview that you can interact with, so you can check a CheckBox for example, enter text into a TextBox and you see what it will look like. If you define complex, dynamic parts within your XAML for instance with some Triggers or converters you even see the reaction which will happen if you change the state of the user interface. The performance is incredible! After the initial load - It just a few milliseconds to get a visible result."