Sandy,
I used to be in the consulting world and implemented SL 7.0 SP1 at three different sites. I asked the support group (plumbline) about this issue at Convergence, as the company I am now with is looking to upgrade to take advantage of the EDD (Electronic Document Delivery) and Windows Auth. They recommended doing a full install on all workstations, terminal servers, or citrix servers running Dynamics SL. The reason for this slowness has to do with the .Net Framework. I am not a programmer so I cannot give specifics.
Do you have a full install on the Citrix Server(s)? If not, you might want to try this first and see if it helps.