The Complete Guide to Registry Cleaners and Optimizers
Windows registry cleaners and optimizers look for banal, often completely fake, things in an immensely intricate system that people are scared of and don't understand. These programs use this position of trust to extort money and mislead users into believing they are required to fix specific problems or improve a flawed system.
Instead, they cause problems and slow systems down - making people believe it's normal for computers to have inexplicable issues. Or, if they never notice the problems these tools cause, they imagine performance increases supposedly gained. This is the placebo effect. I used to think registry cleaners worked because of this. I was wrong. There were cases where it's possible they helped certain users in Windows XP, but for anything since, I can find no reasonable justification for their existence.
I've been the lead maintainer of thousands of collective Windows installations for years as a professional, and before that as an enthusiast on tech support forums. In my job, I routinely go into the registry to look at program configurations and perform specific changes. I develop specific registry configurations that get deployed to over a thousand machines on a regular basis. I have never, in my entire life, used a "registry cleaner" to fix a problem. Nothing I have ever done in the registry, as a professional, would have been fixed by a registry cleaner. Moreover, I've had employees run registry cleaners and completely screw up their computer with issues I've never seen on any other machine.
In fact, registry cleaners will invariably find tens, sometimes hundreds or thousands of "issues" on a Windows system installed from a DVD an hour ago. You can test this yourself, it's a well-known way to demonstrate these programs have no idea what they are doing. They will damage a brand-new installation of Windows just to make it look like they are useful.
The registry is extremely complicated and should only be touched by professionals addressing specific problems. Professionals don't use registry cleaners to fix problems. You never look up a problem on the web where the actual solution is to run a registry cleaner.
That's because registry cleaners don't fix problems.
"Issues caused by these utilities may not be repairable and lost data may not be recoverable."
"We strongly recommend that you only change values in the registry that you understand or have been instructed to change by a source you trust."