> Windows is already horribly inefficient itself
Actually in the early 80s it was almost unthinkable how computing has advanced. On a c64 with less than a 1 Mhz CPU it would respond immediately to keyboard input. Using a 7 Mhz entry model Amiga the preemptive multitasking GUI based OS would always respond immediately with feedback if a GUI button was pressed by the user.
It was almost unthinkable that today we would have multi-core CPUs clocking at over 3000 Mhz and one still has to wait for the OS to respond in various situations with any user feedback. IMO something went horribly wrong with regard to operating systems and of course Microsoft has a large finger in the pie of what went wrong. Much better OS designs from an efficiency perspective is QNX or was the sadly discontinued BeOS.