Hi, first the Render settings in Corona Render works best with default Settings. Renders from the VPR are not the final resolution. the only way to save the full resolution is to render it in Picture viewer in Cinema 4D. Also the viewport render has not the final quality and resolution. When a corona render needs to much time its not a slow render. It is the wrong material setting. My tip is check your materials settings. Corona Render is very exactly on material settings, so you have to know how to setup materials correctly.