regsvr32.dll is a library file that helps to add other DLL files into the system. The file is used to register new DLL files.
Non-system processes like regsvr32.dll 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.