To optimize performance of HDX RealTime conversations in XenDesktop virtual desktops and XenApp sessions, you can increase display memory.
To increase display memory in a XenDesktop virtual desktop or XenApp farm, you increase the Display memory limit of the Citrix Computer Policy Queuing and tossing. The recommended setting is between 8 and 16 MB.
To modify Citrix Computer Policies, you must be a member of the Administrators group on the XenDesktop virtual desktop you are modifying and a Citrix Administrator for the XenApp farm you are modifying.
For more information for XenDesktop 5, see Working with XenDesktop Policies.