Guild Wars 2

Ever since the HoT/Halloween patch my game has been unplayable in windowed modes. As soon as I start moving, the game turns into a slideshow. When I stand still or alt+tab (with a smaller window so I can still see the game running behind it) performance goes back to normal ~70 FPS but as soon as I start moving again, the FPS display in game shows ~13 but it’s closer to 2 seconds per frame. Switching to a full screen specific resolution completely fixes the issue, but I alt+tab often and like being able to see the game with the game window not currently active. Graphic settings don’t affect the issue (best appearance/best performance both are unusable in windowed.

Graphic settings don’t affect the issue (best appearance/best performance both are unusable in windowed).

Are there any known solutions to this?

I’m running on an SSD (both GW2 and Windows 10 installed on it) with a GTX 980, i5 3570k OCd to 4.6GHz and 16GB DDR3.