This mod changes the Mesh of the cobblestone roads and gutters in Novigrad by increasing poly count and adding a displacement map, it also increases the quality of the mesh from further distances so no quality is lost. This mod doesn't change the textures used, only the mesh. I haven't checked for a performance decrease but with a gtx 970 ftw edition at 1920x1080 I get 45 fps on ultra settings with hairworks maxed out.