I am working with Collaboration on a test system. I noticed that with application sharing, even sharing an application like MS Word between two hosts in the same LAN is really slow. When the session host (which is always running the portal on the EP server) releases control to a session guest, the guest could only run the program really slowly, even moving the mouse cursor around is a hassle! And that is the only application session that is running-- with only one session guest.
Anything one could do to improve the speed. The portal host has around 6gb of ram and we have two SAP systems installed. One is ECC5.0 on an ABAP system, and the other is a Java Standalone running the Portal.