Mark Shuttleworth defends the development of the Mir display server on his blog. "Of course, there is competition out there, which we think is healthy. I believe Mir will be able to evolve faster than the competition, in part because of the key differences and choices made now. For example, rather than a rigid protocol that can only be extended, Mir provides an API. The implementation of that API can evolve over time for better performance, while it’s difficult to do the same if you are speaking a fixed protocol."