I was floored to realize how much faster things were. No wait time for a Windows Explorer window to open. Everything was snappy, even after reinstalling games and antivirus. It blew my mind.
I still think it helps, but with a much longer tail on the frequency required. Windows XP definitely grew slow over time though, whether that was due to installing programs, caches I could’ve cleared with CClearner, or more incremental updating. We leave a lot on the OS over time.