How do I fill a bitmap with a solid color?

I need to create a 24-bit bitmap (resolution 100x100 pixels) using a unique RGB color and save the generated image to the disk. I currently use the SetPixel function, but it is extremely slow.

Bitmap Bmp = new Bitmap(width, height);
//...
//...
Bmp.SetPixel(x,y,Color.FromARGB(redvalue, greenvalue, bluevalue));

Is there a faster method than SetPixel? Thanks in advance.