You have an environment map set to 22% on the applied material. Disable this channel in the material.
Regarding the lagging ghosted image you get when rotating in Rendered mode, I am not able to reproduce that here. Let’s try disabling your GPU as a test. Go to Options>Advanced and type OpenGL in the search filter. Then disable Use Hardware Driver… Any change?
I also do not see a load on the CPU here in testing your model. At the moment there seems to be something system specific that is causing this issue but I’m not sure what it might be. What exactly are you doing when you notice this in the Task Manager?