The View menu also provides a Display Quality submenu. Use View to change display style and quality while working on a structure. Options on the submenu are explained in subsection 3.7 - User preferences dialog . High With the High quality display style, movement may be jerky for molecules with more than a few atoms. Surfaces are very smooth.
Lighting is most realistic.
Use high quality when you want the best hard copy, or when you want to look at a static picture. Medium With the Medium quality display style, movement is done in real time for molecules with up to 200 atoms. Surfaces are smoother. Lighting is more realistic. Use medium quality with up to 200 atoms.