Microkernels are often used in embedded robotic or medical computers because most of the OS components reside in their own private, protected memory space. This is not possible with monolithic kernels, even with modern module-loading ones.

Microkernels modularity and abstraction makes it easier to share code, and to use the same microkernel in different OS implementations.

Monolithic kernels tend to be easier to design correctly, and therefore may grow more quickly than a microkernel-based system.

microkernels are slower than monolithic. Mach is like 15% slower than a monolithic kernel like Linux.