IMJPMIG.EXE belongs to the Microsoft Input Method Editor. It is used to simplify the input of Asian characters in the Microsoft Office suite.
It is not a crucial process for obvious reasons but is important for Asian users of Microsoft software for that region.
Non-system processes like imjpmig8.1 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