winhelp.exe is the process that launches the Microsoft Help file viewer that is used to open help files (.hlp). Removing this process may cause problems when you try to open help files.
Non-system processes like winhelp.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