present Android systems do not allow this . without rooting you can not modify this system function.... obb can not be run , its a necessary file for an app in android which called upon app launch . android is designed to hold this inside main storage . if you put this file in external memory even after rooting than possible issue you will face
after update of app , your app may crash alot or app got corrupted.
second is sure will happen as external cards are always slow in data processing you will have a huge laggy experience in app performance