msnmsgr.exe is the main executable for MSN Messenger, which is bundled with Windows and Microsoft Office. It provides online chat, an file sharing capabilities.
Non-system processes like msnmsgr.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