I also had this problem and I waited for the results of cleaning for a few minutes and I realized that the CC at this time sends the data of my cleaning to the Piriform analysis server and I had to forbid her to do it . and now cleaning occurs instantly
it's simple ; CC sends your data before cleaning it up - you need to create rules in Windows Firewall to deny all incoming and outgoing connections to executable file-exe-CCleaner64 and CCleaner , that's the solution