The work is done by the fahcore, not the client process, so changing the priority on the client has no impact on performance. The priority for the fahcore is set to βIdleβ by default (but displays as normal in Task Manager). The client is already designed to use all spare CPU cycles, so changing the Windows priority is unnecessary. If the FAH client is competing with another process running at βIdleβ such as a background AV scan, there is a client option to run at a βLowβ priority.