There is a delay of several seconds before the Windows Server 2003 Object Search dialog appears when you select objects from Active Directory. You did not experience this delay on Windows 2000 or Windows XP.
This behavior occurs because an enhancement to list trusted forests in a remote forests global catalog causes object picker to always call the forest root domain controller.
This delay may be more noticeable if the port to the forest root domain controllers are blocked.
To reduce the delay, open the ports for the Local Security Authority service to the forest root domain controllers by downloading the Port_Requirements_for_Microsoft_Windows_Server_System.xls package.