>> If I am remember well, MS Windows (the operating system) does have a
>> micro-kernel, but is it more efficient with an extra layer of
>> intercommunication?
>
> Windows NT is based on DEC VMS, not a very modern OS ;-)
> https://en.wikipedia.org/wiki/Dave_Cutler

Based on VMS, right, like Linux is based on Multics ;)

Seriously, efficiency isn't the prime consideration for microkernels.
Reliable performance is a better key term.

Arnt