Basically, such "optimizer" programs create problems for users. And with the registry cleaners they use, most often, they create more problems than they fix. Every different registry cleaning tool/optimizer will identify different stuff that is so-called "bad" for your computer and until YOU can identify which of those items are OK to delete, I wouldn't let an automatic tool remove them for you. And frequently, if you let the tool run a second scan after it's finished removing stuff the first time, it will identify more stuff, and more stuff, etc.
A quick search of these forums will show you the problems that others have lots of problems with many of the iolo.com stuff. The link below is just one such topic:
https://www.cnet.com/forums/discussions/having-to-pay-to-upgrade-to-system-mechanic-16/
Hope this helps.
Grif
I had had sooo many issues with my laptop and thought I was going to throw it away, so to speak, but I found SYSTEM MECHANICS 16, and IT WORKS GREAT!! I would recommend it to ANYONE! great and easy to use, install, etc.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic