desktop customization - Why would a solid wallpaper cause a Windows PC a long time to login?

I have been using Windows 7 Ultimate 64bit in my Dell Inspiron 620s (Intel Pentium Dual core, 2GB DDR3 RAM). My PC used to take a long time to login and it’s only for my admin account; other user account works well.

Then I found out that the slow login was due to the wallpaper I used; I used a simple, black solid color wallpaper available on the system. But when I changed it to something else, my PC became fast.

I just want to know why it is so?

Answer

Simple solutions:

1. There is a Hot Fix available (Thanks to magicandre1981 ).


2. Change the wallpaper from solid colour to an image that has a solid colour.
   

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Another Solution(Requires editing Windows Registry):

Configure the value of the DelayedDesktopSwitchTimeout registry entry. This value determines the time-out interval of a session before Windows 7 or Windows Server 2008 R2 switches between sessions.

To configure the value of the DelayedDesktopSwitchTimeout registry entry, follow these steps:

1. Click Start button, type regedit in the Search programs and files box, and then press ENTER.


2. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System


3. Double-click the DelayedDesktopSwitchTimeout registry entry.


4. In the Value data box, type 5, and then click OK.

This answer is reproduced from this Microsoft support article.