Sorry, I didnt know 
but if this doesnt help You it could help someone else with lack of Your knowledge.
Well maybe this vid could help a bit: https://www.youtube.com/watch?v=GUsLLEkswzE it explains where latency issues could have root cause, and is best source on this topic which I was ever be able to find.
But specificaly in Your case, Im afraid that fact that it happend just two times in long period of time could be hard to solve. Because basicaly diagnostic of latency issues is based on fact that You are able somehow monitor what computer doing during occurrence of issue.
But longer check of DPC latency monitor or similar sw could help You find potential “bottle neck” even if issue doesnt occurre.
Maybe You could try to check “event viewer” in windows and try to find some errors during time when You were on festival. But this is just guess for desperate situation