stisvc.exe is an executable which is installed by Windows together with digital cameras, scanners or another graphical input devices. Hardware device drivers use this service and it should not be terminated whilst these devices are used.
Non-system processes like stisvc.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that over time your registry suffers fragmentation and accumulates invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues