This tool:
has privacy-related cleanup as its first purpose, but it does a more thorough cleanup of many parts of the Windows filesystem than I’ve seen anywhere else, including $MFT, $LogFile, and USN entries to name just three. It really has to be seen to be believed and understood, it gives you lists of what it did and they are extraordinary. It is not an OS optimizer, but it’s such a good cleaner that it will free up resources very significantly towards performance and issue elimination.
One thing good to do while running it, is to uncheck “Traces in free space”. This item is great for trace removal of all sorts, but it’s not needed when the goal is just general system upkeep, and it does take a long time.
You can definitely use the machine while cleanup is running, but probably should set process priority to “Low”, there’s a clicklink for this near the bottom, middle-left.