My 6 plus does pretty good on it, but it is getting on its last leg so I’m not sure if it’s my phone or iOS 12 on it, I do notice some random freezing with mine every now and then where the screen doesn’t respond for about a minute then it’s fine. I know 6/6+ phones have digitizer issues though so I’m planning on upgrading to the Xr soon. It is definitely quicker for the most part than iOS 11 though.