It's not a bad app by any means, but I wanted to post a quick reminder that registry cleaners are not in any way a substitute for restraint on the user's part in not trying out a ton of software to see if you might like or need it. That's the most common cause of registry bloat. Instead install VirtualBox, VMWare, or use Windows Hyper-V to run a VM, a pretty much disposable copy of Windows running in a pure software environment. Sandboxie will also work. Win10's sandbox works too, but I dislike the Win11 version... Windows sandbox takes up a lot of space, though less than 1/10 the space of a Windows VM. However, the space used by Win11's sandbox keeps growing, with new images added alongside the old ones. And it uses VBS [Virtualization Based Security], which is a proven drain on your PC's/laptop's performance, with no way to turn it off other than removing the sandbox.
Back to registry cleaners, what they can do is search for and remove what are basically broken links. If a registry entry refers to a file that doesn't exist at the listed location, that's considered broken, & registry cleaning apps will gladly remove that entry. The same goes for registry entries that refer to another registry entry -- if that target entry is missing it's broken. If there's enough broken entries removing all of them can make a noticeable difference, but it takes an awful lot of them before you make a dent in the registry's total size. If you have unlimited time on your hands you can do better, since often the entire key containing a broken entry, maybe 1/2 dozen entries total, can be deleted.
OK, but what about safety? Software developers can add whatever they want to the registry. Software is also often updated, with new programming code added. But apps are rarely completely rewritten, so some old code is left in place, even though it serves no real purpose. That means that an app may require a registry entry that otherwise appears to be broken. That entry may serve no purpose whatsoever, but the app's code checks to see if it's there, and if it's not, the app may crash or refuse to run. If a registry cleaner removes that entry, that app's broken. Wise Registry Cleaner Pro can back up registry entries before it removes them , so restoring that backup *should* get that app working again. Unless the now broken app prevents Windows from running, e.g., it's tied into one of the hardware drivers. Now you're sunk because since you can't run Windows you obviously cannot run Wise Registry Cleaner Pro to restore that backup. Wise Registry Cleaner Pro also creates a Restore Point, which *should* also work to put everything back the way that it was, and you can restore it if Windows won't start, but Restore Points don't always work. If you want to be very near 100% safe do a disk or partition image backup first that you know you can restore.
Will cleaning the registry help? Yes, but you may never notice it. Windows reads & writes to the registry constantly, and the smaller it is the less time it takes to read into memory and read & write entries. But unless your hardware has very little RAM & the registry is really huge, this all happens so fast that shaving off milliseconds is not going to be noticeable. Some reports say that using a registry cleaner fixed stuff. That is possible. If you have a running app, driver, or service that's behaving badly, and cleaning the registry breaks it, that can be a win. For a registry entry or entries to actually break something they have to be required and missing or incorrect, and the only way you'll find those entries is to compare the registry to the registry in a copy of Windows where whatever app runs correctly. [It's usually faster to remove the app that won't run, scour the registry manually to remove all traces of it, and reinstall the app, though that sometimes does not work in my experience.]