About Prioritizing and Directing Traffic Flow : About QoS for Citrix
  
About QoS for Citrix
QoS does not support packet-order queueing or latency priorities with Citrix traffic. We recommend using either the Autonegotiation of Multi-Stream ICA feature or the Multi-Port feature to classify Citrix traffic.
You can classify Citrix traffic using QoS to differentiate between different traffic types within a Citrix session. QoS classification for Citrix traffic is beneficial in mixed-use environments where Citrix users perform printing and use drive-mapping features.
Latency priority allows you to assign interactive traffic a higher priority than print or drive-mapping traffic. A typical application priority for interactive Citrix sessions, such as screen updates, is real-time or interactive. Keep in mind that priority is relative to other classes in your QoS configuration.