Question Best way / optimized way to render texture swaps on faces

I'm trying to make facial animations using this technique. Eyes blinking, mouth opening, etc.

I've found a lot of videos describing this and understand some ways to do it.

But from what I understand, swapping the texture loaded into the material at runtime has a lot of over head?


I was trying to figure out the most optimized way of doing this:

I am just wanting to animate eyes and mouth.... I would prefer having them (animated facial parts) in some atlas, for runtime optimization and simply cycle through them somehow.