Why do layered tend to be less efficient than monolithic? (Self Review)

There are two types of operating systems that we discuss here.

Monotholic

It is the types of operating system, in which all the operations are performed at single place that is known as kernel.

Layered

In this operating system, all the tasks performed in different layers of operating system, by assigning task to each layer.

It is difficult to manage tasks according to the functionality of the layer and managing on them different layers. so that is reason layered tend to be less efficient than monolithic