Compared to what? Apple or the mobile OS du jour? Most other operating systems in commercial use, and we can look both at the commercial unices and the embedded

Compared to what? Apple or the mobile OS du jour? Most other operating systems in commercial use, and we can look both at the commercial unices and the embedded stuff, supports APIs much older than Windows itself. Support for the Win16 API has been abysmal recently. My limited experience of old DOS and Windows applications is that they often run better under dosbox or wine than native.