It sounds like you’re asking whether you can divide a 1024x1024 texture into 16x16 squares and only use resources for the square that’s being actively used in the diffuse? From what I understand no, that isn’t the case. The 1024x1024 texture will be used/loaded as a whole, regardless of whether only a portion of it is used in your uv space. If your textures are just solid color, why use textures at all? Use a constant 3 parameter in UE4 and set your colors that way. You’ll also be able to change the colors through instances. =)