Add a timer or an estimate which explains how much time the process will take.

The cleaning processes take differing times and it would be nice to know how much time exactly is left or to have an estimate of how long the process will take. For example: "Registry Cleaner: Cleans and repairs invalid registry entries and errors. Time needed: A couple of minutes depending on your system."
Or a simple timer by the point of the process, for example "Approximately 1:20 minutes remaining."