I wouldn't.Avira Security offer me to delete unused registry entries that left by Windows when I doing smart scan.
The short answer is no it doesn't affect performance and it won't damage Windows, but it may make some apps complain.The question is in the subject.
Is this affecting Windows performance for good, or damaging Windows?
If you do decide to clean the registry make sure you do a registry backup before doing the cleaning.The question is in the subject.
Is this affecting Windows performance for good, or damaging Windows?