This conversation has been merged. Please reference the main conversation: Photoshop CC 2018 19.1: The rubber band being shaky
He includes a video to demonstrate the problem.
I checked both my Mid 2012 Macbook Pros and noticed this problem in CC 2018, but not in CC 2017.
This seems like a bug. Perhaps other users can see if that's the case and I hope the Product Managers can have a look at this.