Pure Cast vs Impure Cast?

Is there any difference between Pure Cast and Impure Cast performance wise? Too many casting make the game thread goes high (a spider web perhaps), so a pure cast will do the same? or should I use BP Interface or Event Dispatcher. My main goal is to avoid Spider Web like object reference.

In blueprints I doubt there is any difference in performance between pure & impure casts. I would suggest using variables to store actors + objects after casting to avoid doing more.