So we are looking at this issue and any time we see this internally, it is investigated as a priority. However I believe people are seeing different issues and describing them all as "lag".
Since 7.2 M1, there are 2 known fixes for mouse lag (or more correctly - momentary screen freezing for about a second). These are in the latest 7.4 beta on our Windows 8.1 forum here:
http://displaylink.org/forum/showthread.php?t=61769
Can you try this, as there are known fixes in this that might help your use case. If not, can you post your logs?
Thanks
Wim