I didn't guaranteed anything.
I am not a avast employee.
i dont know what basis you are saying clean up is working
What is making you think it isn't? It is scanning and cleaning up the things it found. That is exactly how it is supposed to work.
A slow system doesn't have to be caused by malware.
It can also be caused by e.g. dust making the hardware too hot.
If you attach the Farbar log files to a post, we can check if there are things loading/running that shouldn't.