What do registry cleaners actually do?

Question

Possible Duplicate:
Is it worth cleaning the registry?

Alright, I've been wondering about this for quite awhile. I have heard both sides of the argument and quite frankly I am uncoconvinced that running a registry cleaner actually does anything of value to systems they are run on.

I am under the opinion currently that running them often causes more harm than good and it would be great to get some feedback.

Can anybody explain to me any benefits or provide any substantial evidence supporting the use of registry cleaners in general rather than the usual "Oh it makes your computer waaaay faster" argument?

Through my googling I have found several arguments written agianst the use of registry cleaners. See here and here.

Basically to summarize what I've taken from these articles is this:

1. If you don't run a registry cleaner you will decrease the risk of corrupting registry hives. If you run registry cleaners you certainly increase this risk.
2. There may be minimal gains by either defragging or cleaning the registry, but these gains are almost impossible to measure or calculate.

So should I continue to ignore registry cleaners? Can somebody enlighten me on this subject?

Answer 1

Let me quote Mark Russinovich, Sysinternals:

No, even if the registry was massively bloated there would be little impact on the performance of anything other than exhaustive searches (ed. of the registry itself). [...] I haven’t and never will implement a Registry cleaner since it’s of little practical use [...] and developing one that’s both safe and effective requires a huge amount of application-specific knowledge.

Given that he has worked on a part of the kernel and provides many useful troubleshooting tools, you can with no doubt trust his words as he sure knows what he is doing. His blog is worth following...

The best thing you can do is to run ERUNT and NTREGOPT which will back-up and defragment your registry, although the effect is like 1%... Other than that, do not fix something that ain't broken!

The only reason I would attempt to remove large amounts of data from the registry would because I found the registry to be the culprit using tools like Process Monitor and Windows Performance Toolkit.

As for the exhaustive searches, my registry indexer is a possible solution.

In short: You should ignore registry cleaners unless you know what you are doing...