The quality of the normals on an object are determined by vertices. You can use a normal map to compensate, which will incur a bit of a performance cost in the PIXEL shader. Adding more vertices will add a performance cost to the VERTEX shader. These two run side by side to render everything you see. It would actually be the most optimal to use more vertices to get an acceptable representation, but if you want absolute perfection, the texture method will be more accurate than vertices. Performance is a constant tradeoff between pixels and vertices. It’s up to you to figure out what you’re going to save, and what you’re going to use.