Applications that use the ramp driver can sometimes improve performance by using the D3DTBLEND_COPY texture-blending mode from the D3DTEXTUREBLEND enumerated type.
To use copy mode, your application's textures must use the same pixel format as the primary surface and also must use the same palette as the primary surface. Copy mode does no lighting and simply copies texture pixels to the screen. This is often a good technique for prelit textured scenes.
If your application uses the monochromatic model with 8-bit color and no lighting, performance can improve if you use copy mode. If your application uses 16-bit color, however, copy mode is not quite as fast as using modulated textures; for 16-bit color, textures are twice the size as in the 8-bit case, and the extra burden on the cache makes performance slightly worse than using an 8-bit lit texture. Again, you can use D3dtest.exe to verify system performance in this case.