Comment by brudgers

Backward compatibility is an OS performance metric. Maybe sales is too. Microsoft has to think long and hard about any kernel change. In some irony, Microsoft doesn't own the Windows code, and any individual can own the Linux kernel - i.e. Windows lacks forks.

That Microsoft discourages individual junior developers from cowboying, is a point in their favor. Optimization for its own sake is not what benefits their users - real research does.