When working with wpf/silverlight in visual studio 2010 the XAML designer kind of slows you down. Because it takes forever to load and reload. A simple solution is it to open your xaml with “open with” option and choose “use source code (text) editor” instead of “xml editor chooser” and then set it as default option. In this case XAML designer won’t try to render and all those ugly lags will go away.
When you actually need the design window you van rightclick the file and select “Open in expression blend”