"Anyone can write programs for windows, and we will break our backs giving you as many optimizing API's as we can come up with"
In that regard, windows is a lot more "open" than the mac. I mean just comparing visual studio to Xcode is a joke. Just making a program on a mac where you click a button that makes a sound take twice as long as it does on the PC using visual studio.
Now to optimization. Lets take this API structure and look at Flash. On the mac, EVERY frame on flash video ends up having to be rendered by the CPU. On the PC, because of the better API structure, various tasks are actually broken down to a more efficient manor. (This is all according to Adobe).
You have no clue what you're talking about.
Oh, and nice C# fanboy contrived example.