If you are running software that's using a game-engine, it's possible that the mouse movements are too sensitve to navigate properly. This is often the case when you can "walk around" in a 3D model.
Herefor a simple setting can be changed in the Citrix Receiver Preferences.
Note that this option is only available for the Citrix Receiver, not for the HTML5 client.
Click on "Apply" (and/or "OK") and test if the mouse movements are optimized.