Finally, the obvious optimization is done for .NET, in this case for Windows Phone 8 (only).
Programs build on Microsoft .NET platform are deployed in "IL" code,
and "JIT" (Just In Time) compiled on the computer where are running.
That takes (sometimes long) time, and and most computers identical anyway...
Maybe a good idea when Java was used for small applets and slow connections, not anymore...
Announcing the release of the .NET Framework for Windows Phone 8 - .NET Blog - Site Home - MSDN Blogs
"For Windows Phone 8, we adopted a new code generation approach that is much better suited to the phone, both to deliver higher performance and to save battery life. Windows Phone 8 apps are compiled to high-quality ARM code before they are downloaded and deployed on end-user devices. They are compiled in the Windows Phone Store, with an optimizing compiler that does not have to satisfy the time and power constraints of a just-in-time (JIT) compiler. As a result, end-users will enjoy very fast app launch times on Windows Phone 8."