acsd.exe is a component of AOL. It is process running in the background and it automatically reconnects you to AOL if you are being disconnected.
Non-system processes like acsd.exe 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.