My normal fps is around 160 when playing and whenever i turn the camera or even move my mouse over the gw2 screen…fps would drop to 1-5 fps. after a lot of trouble shooting and driver updates i found what the issue was. Polling rate for my mouse was set to max (500). I turned it down to 125 and the lag has completed stopped and my fps is stable again. hope this helps someone as it took me days to figure this out and i’ve seen a lot of posts around other forums about this same issue