Thanks for sharing the file. You didn’t have the Luminance channel settings with your original post, but now I see that you are using a cel texture with “Use Bump” enabled, and that is what is causing the fizzing effect. The render settings aren’t an issue.
If you want that grainy shadow look to remain still when the object turns you’ll need to get rid of the bump in the material and try to get it with lights and shadows, which could be an interesting endeavor itself. As long as the bump is there, when the object turns the light will catch the changing texture and cause the fizzing. What is the look that you’re going for?