MarkupCompilation: XAML, BAML, .g.cs Details

Rob Relyea: "WinFX allows you use XAML to declaratively define your UI, interactive media, or document. XAML is a great way to define these things. However, XAML isn't what we'd prefer to use at runtime.

With HTML, parsing of the .html file is done at runtime. This leads to the following problems:
1) the runtime spends a lot of energy to convert markup into objects
2) often errors are caught by the user, not the developer/author

Avalon allows runtime parsing of XAML, however we think you'll see the benefits of compiling most of your markup."