The Registry is most important thing on Windows system because it will controls how your Windows appears and how it behaves. Most applications today use registry to store configuration and other important data. When you install application, new registry entries created.
But it does not always work that way. Sometimes you find that several applications fail to remove their own registry entries. These entries will become obsolete.
After a long period, after installing and uninstalling a lot number of applications, your Windows registry may contain a large number of obsolete entries. These will significantly increase the registry size and thus will slow down your computer, because Windows will need more time to load, search, and read data from registry.
To keep your computer in top performance, it is recommended to periodically clean your Windows registry
new in v6.2.1
General: Upgraded SQLite library to version 184.108.40.206.
Quick Optimizer: Fixed problem when reading FireFox 4 database files.
Quick Optimizer: Improved support for Internet Explorer 9.
General: minor improvements and bug fixes.