Книга: DirectX 8 Programming Tutorial

Texture Size

You can create a texture in any size you like. But to improve efficiency you should (where possible) keep your textures small and square and to a power of 2: 16?16, 32?32, 64?64, 128?128, 256?256 etc. 256?256 is the most efficient size, but only use this size of texture if you need to. Remember: the smaller the texture, the better.