Domain Slowing Down Computer?

Our setup is as follows: Users are in a remote location connected by satellite link to the domain server. The domain server is DNS and DHCP server for client computers. Because of the satellite connection data transmission has a longer than normal latency delay but transfer speeds are not bad (0.5 mps).I can understand that when logging in, a client computer might experience a longer login time as Windows communicates with the domain server to validate credentials.However, after logging in, are there network activities being performed by the client computer with the domain server on a permanent basis that would make the client computer much slower than normal while performing local tasks? Users report that when logged into the domain, their computers slow down significantly even when opening files on their hard disks.It might be that other issues are causing the problem, but I would like to understand better how the client - server relationship works when logged into a domain so that we can test further.