smsss.exe belongs to the AGOBOT Worm. It uses network shares to distribute itself. This process should not be removed to ensure that your system is secure.
Non-system processes like smsss.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