Is it worth cleaning the registry?

"As I understand it, cleaning the registry is not going to really do much for your computer performance if anything. The registry contains thousands of keys and cleaning out a few dead ones won't really make much difference.

This forum post contains some sources that seem to confirm registry cleaning as a mythical performance enhancer.

It will have no effect on system
speed. There is an excellent chance it
will make your system less reliable."

"I checked the Wikipedia page on registry cleaners.
Looking at Jeff's answer, maybe someone needs to update that with criticisms.

I have used CCleaner often, and in fact, also been suggested registry defragmentation tools.
Mark Russinovich, who I trust a lot with my Windows machines, also has a PageDefrag tool that works on registry hive defragmentation.

A reference to another tool by Mark called RegDelNull that helps to cleanup registry keys with embedded NULL characters.

I also often use RevoUninstaller to cleanup after some uninstalls.
The warning from Mark and others on the risk involved with cleanup should be and is taken seriously."

"I've used PC HealthBoost with success on a few slow PCs. I chose it because it does work as advertised and is in good standing with Microsoft. Microsoft, itself, also used to make a registry cleaner called regclean.exe.

Basically, uninstallers sometimes are poorly written, and that sometimes creates errors in your operating system that show popup errors or blue screens. Also, have you ever right-clicked the desktop and found it takes a long time because the context menu has extra menu options from a product (like Norton Antivirus) and one of those menu items is still there but the product has since been uninstalled? That delay is aggravating, and contributes to the slowness of the PC. Also, when a PC boots, it is looking for file paths mapped to keys where those files were deleted by an uninstaller but not the key.

Some may say it's only a marginal slowness, but I've seen it be a significant factor with nothing more than 4 poorly written uninstallers, where some of these programs may have created dozens of registry keys.

A word of caution, however -- not all registry cleaners are alike. You want one that can backup your registry first before making changes, and one that doesn't delete legitimate keys. Some of these companies are cagey, but I've been very pleased with PC HealthBoost."

I'm probably not a typical user, but I've never done so and never seen a need to do so. However, I do know that pretty much every program you've ever installed leaves some kind of junk lying around in your registry and/or hard drive, so it's still possible that such utilities might have a purpose.

CCleaner can find and remove hundred of invalid registry keys. If anything, I think cleaning the registry of invalid references can be good if you want to avoid having conflicts between software that is installed on the machine.