I've recently reinstalled Photoshop CC on my Windows 10 Pro PC, and after working a bit with it, I noticed a strange problem.
After the first 20 actions (selection, brush strockes, etc), any line that I draw with any tool looks jagged or stepped. Every curve drawing tool from Lasso, including all brushes, to Clone and Blur tools are affected by this issue.
No matter if I connect the pen tablet or just use the mouse, they produce the same lines. This doesn't occur anywhere else (Animate draws lines just fine), so I don't think it is a mouse or pen tablet problem.
My guess is that there could be a conflict with my two graphic cards, a high-end Nvidia GTX 980 and a mid-end Nvidia GT 710, but I haven't tested out with just one of them. Could this be the issue?
If you have two different enabled GPUs in you system Photoshop may have problems has been posted many times. I would also think that system interrupts and conflicts could interrupt interfere with time sensitive real-time execution brush strokes require. Brush spacing and speed of stroke can also play a part.
It seems that this only happens while slices are visible. After hiding the slices I made, Photoshop was able to draw smooth curves again.
You may also see thing like that when you have layers and guides and snap to on and use a brush