Disk defragmentation can move data to adjacent areas of the disk and speed up access times. A similar philosophy has recently been applied to the Windows Registry, although many registry scanning programs, registry cleaning programs, and registry defragmentation programs simply put spy ware or viruses on their computer.
Registry defrag programs will not speed up access time to the computer. They legitimate ones will reduce the risk of errors down the road. They can also remove old or outdated entries. Almost every piece of software installed on a Windows computer will make changes to the Windows registry. When a computer owner uses the add/remove tool from the control panel, it usually removes these registry entries as well.
This process does not always happen cleanly, and many old entries stay in the registry long after they are no longer needed. These entries that no longer point to a program are usually harmless, unless the same entry was needed by another program for proper operation.
A registry defrag program will cause these slight errors to point to the program that now needs them in addition to reducing the size of this vital system file. A user who knows how the registry works inside and out may be able to do a registry defrag on his own, but this is a time-consuming process. An automatic scan eliminates the hours an advanced user would need to take in order to check the thousands of entries that get deposited in the registry. Even if you know what you are doing, changing a registry value is not a good idea. Change registry values on your own only if the other option is reinstalling the Windows operating system.
Running a registry defrag program is not always necessary, but it is a good idea to include this scan as part of regular system maintenance. Be very wary when downloading such programs and only get them from a trusted site.