I have GT650M SLI system. all worked fine and smooth. But once i've noticed fps drops. Typical situation: 60+ fps, then drop to 0-4fps for few seconds, then fps back to normal 60+. And this issues only in GW2. All other games runs perfect. After some research i found that it's nvidia driver issues. For make it smooth again you just few tweaks: 1. Switch PhysX to main CPU (by default it's calculated with GPU) 2. Switch "Power Management Mode" to max performance mode. 3. Option "Maximum pre-rendered frames" switch to 4. 4. run GW with "-cuda" option. And it's again smooth and fine (fps increased from 60 to 80) You can make this tweaks only for GW2 (application settings tab), and other games don't be affected with this settings.