Ddraw RGB display

I can see that YUV video data is displayed with direcdraw, which does not consume CPU at all. I just want to try the RGB display in ddraw. I found that my computer graphics card does not support 24-bit off-screen surface creation, we had to create a 32-bit surface, and then copy the 24-bit RGB data to the 32-bit off-screen surface. The bgra format is now on the BLT to the main surface, it is found that the CPU usage is higher than the display speed directly using GDI (setstretchbltmode, stretchdibits), because the copy data consumes a lot of CPU. I don't know what the performance will be if the video card supports a 24-bit RGB surface!