The Registry is the heart and soul of any Windows system. It contains information that controls how your system appears and how it behaves. Most applications today use the registry to store configurations and other important data. When you install an application, new registry entries will be created. These entries automatically will be deleted when you uninstall the application. Unfortunately, this process does not always work. Sometimes, some applications fail to remove their own registry entries. These entries become obsolete.
After a long period, after you install and uninstall a number of applications, your Windows Registry will contain a large number of obsolete entries. This will significantly increase the registry size and thus slow down your computer, because Windows will need more time to load, search, and read data from the registry. To keep your computer at top performance, it is recommended you periodically clean your Windows Registry.