One of the most vital methods of fixing computer errors and optimizing your computer for increased performance is by cleaning the clog out of your registry. There are so many people who use computers in this day and age who has never even heard about the registry let alone how to repair and optimize it.
If you do not know yourself how important it is then I'll explain it to you in english terms. Think of the registry as a file cabinet which holds data to everything. When you install programs data entries are made into it which is used for settings and other recent data such as recent files you've opened in the program.
This is just a small example, however, because there is more data being created within just those for some programs. Now once you uninstall programs a lot of them tend to leave the data entries in the registry which causes errors and clogs it.
Once it is clogged with old entries and errors this will cause your operating system to have system errors. Which can cause slowdowns, your computer freezing up, or even just randomly restart with a blue screen.
Now as for looking for a registry cleaner. This can become quite a task because there are so many that are popping up on the internet every day. Many of them that I have personally tried just either did not do the job properly or in some cases would try to delete data entries that was made by my operating system.