Is a good design to use async from controller to repository?

Is a good design to use async from controller to repository?

I have the following "standard" desing of my project:

ASP.NET MVC (View Models) -> Business (Entity) -> Repository (Entity) -> ORM            

With the "async advent" I see that it improve the web performance with async calls to controller. But talking about Repository, is a good idea to extend the async to all layers?

Async Action calls Async Business Method, Async Business Method calls Async Repository Method, Async Repository Method calls Async ORM Mehods.

I'll have a lot of threads, that can overload the CPU and instead of having a quick application I have the inverse?