Sorry to hear about the mouse cursor lagging. Could you please try deselecting "Use Graphics Processor" located in Photoshop's Preferences > Performance, then relaunch Photoshop and let us know if it helps?
I've noticed that other adobe programs sometimes have that issue, and I found the reason eventually -
Apperantly it was an issue with G-sync, when disabling G-sync thing work smoothly.
So I disable it while working on Adobe programs, and then turn G-sync back. But I hope this issue will be addresst by Adobe, I've learned online that it's a common issue with the latest versions of adobe (started around September).