Why did Windows 7 log on slower for months if you had a solid color background?

Summary

Personally, I use a solid color background. It was the default in Windows 95,¹ and I’ve stuck with that bluish-green background color ever since. It’s sort of like my comfort food. Imagine my surprise when someone pointed me to a support article titled “The Welcome screen may be displayed for 30 seconds during the logon process after you set a solid color as the desktop background in Windows 7 or in Windows Server 2008 R2.” Why is logon slower with a solid background? After your logon has been authenticated, Windows sets up your desktop. There are a lot of things going on. The taskbar gets created. The components that are responsible for various system services are loaded and initialized. The desktop window is created and filled with icons. And the desktop background window loads up the desktop wallpaper and paints it to the screen. The logon system waits for all of these pieces to report that they are ready, and when the all-clear signal is received from everybody, or when 30 seconds have elapsed, the logon system switches away from the Welcome screen. Given that design, you can imagine the reason for the 30-second delay: It means that one of the pieces failed to report. Perhaps it was written like this: InitializeWallpaper() { if (wallpaper bitmap defined) { LoadWallpaperBitmap(); } } LoadWallpaperBitmap() { locate the bitmap on disk load it into memory paint it on screen Report(WallpaperReady); } The code to report that the wallpaper is ready was inside the wallpaper bitmap code, which means that if you don’t have a wallpaper bitmap, the report is never made, and the logon system waits in vain for a report that will never arrive. Later in the article, it notes a related article that calls out that if you have the “Hide desktop icons” group policy enabled, then you might also suffer from the 30-second delay. Group policies are susceptible to this problem because they tend to be bolted on after the main code is written. When you have to add a group policy, you find...