CCleaner is the best tool that you might want to use if you want your computer to be clean at any given time. The tool is free to use and it gives you access to a lot of different options that you can further customize in order to squeeze the maximum amount of performance out of your computer with no risks at all. As long as you know what you are doing, of course. If you want to fully understand the features of CCleaner you should take a tour of the help file in order to find out exactly what each of the available options allow you to do.
CCleaner is mainly a registry cleaner that will allow you to get rid of every unwanted and useless entry in the registry, remnants of uninstalled applications or from similar activities. Of course, you are able to do a back up of the registry before the files are deleted, but you will not encounter any problems at all, this being a proof that CCleaner knows exactly what are the files that must be deleted in order to make the computer run faster and not crash.
CCleaner has also other cleaning tools that will allow you to get rid of unwanted files on the computer, such as temporary files, cookies and other things that in time, can pile up quite a bit and can eat up a lot of space. There are other features included in this application such as a start up cleaner, meaning that you will be able to set which applications you want to start when the computer is turned on. This can allow you to avoid congestion of the memory and the CPU as you can later launch those certain applications manually instead of having them all starting at the same time.