Hi, I encountered some serious loss of fps in gw2 over the past week. I restored my nvidia graphics drivers from the latest (337.88) to the previous (335.23) and it has seemed to help. I also did try the beta drivers (340.43) but they seemed much the same as the current one.
I am using a gtx 560 and running win 8.1. I know a lot of people are reporting performance increases with the latest nvidia drivers but my experience has been the complete opposite. Do not know if it is card related or what.