ADService.exe is component of the Iomega Zip Drive drivers. It can be used to automatically run the content of the Zip Drive on insertion.
Non-system processes like adusermon.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that your registry has suffered fragmentation and accumulated invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues.