On first question, You may want to change Ease to B-Spline, or switch noise to 2D instead of 3D. Another option is to increase the details of the noise textures. On the second question, It depends on which option you are using. If it’s Optix you can try changing the passes to Albedo or Normal instead of the default of both. Since it’s displacement, I think it would be Albedo. I could be wrong, because I mainly work with eevee. Another option is to increase noise threshold. For example: default is 0.01 maybe try 0.015. It will be different depending on your GPU.
