ntbackup.exe is a part of the Windows Backup Utility used to back up files and folders. This process should not be removed while running a backup using the default Windows Backup application.
Non-system processes like ntbackup.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