The load performance is degraded by the process that loads the predefined themes (themes that are supplied with our controls like Office2007Black or Office2007Silver for example). There are a lot of bulky XML files to be processed that load the theming for all instantiated UI element types like buttons, tabs, menus, etc. We are working on a major optimization of the performance and our latest achievements proved to be optimistic.
In the case with the ribbonbar, we tested a scenario that includes a ribbonbar containing 50 chunks and more than 500 buttons. It takes up to 3 seconds for the application to start and the ribbonbar to be displayed on a average performance PC.
There are still slight performance issues with the layout system but we are working on that one too. The rendering system also will be polished. We are also optimizing the memory footprint of our controls, you should expect a nice surprise there too.
All mentioned above should be available in the next release. Any feedback on the topic is most welcome.