I think he's talking about perceived UI speed. Things like moving the mouse, starting an application or dragging a window respond fast on Windows because of how

I think he's talking about perceived UI speed. Things like moving the mouse, starting an application or dragging a window respond fast on Windows because of how the system is set up (mouse cursor practically has top priority and graphics are hardware accelerated). This is especially noticeable on slower hardware and can cause a machine to feel 'snappier'.