I tried to figure out if this was real, and the closest I found was this article where setting a solid color background in windows 7 would cause up to a 30sec delay during login. The solution was apparently to make a small image in the color you wanted, and tile that image so that it would cover the whole desktop.

Here’s a hackernews discussion on it, includes some other fun stories like how windows 95 progress bars would complete faster if you were wiggling the mouse the whole time.