I am not sure. JV i suppose from the Wineforums is the one who checked Guild Wars 2 during the first Beta Weekend. He made a Youtube Video and used a Overclocked cpu. He got a good Frame rate. Even with all settings on. But he used just wine.
I bought a new Geforce to ensure the great FPS. But with this Card i can Confirm that the game will run the same, cause of nearly no usage of the gpu. If i have the PowerMizer on Adaptive i got just Performance Level 0. And even if i switch manual on the highest level i don't got extra frames.
Still with my Quad Core at 2,5 Ghz i got a nice Framerate. With lowest settings i got the stabilized 20 fps i could get. Setting higher the fps are not more less without moving.. but i hate it when the frame rate breaks every 5 seconds to 5 or 10 fps.
Actually i play the game with wine, cause i know how to launch thee game with a single command. I will suggest to made some more Tests with Crossover if i find the time. Playing the game (even with wine and with 22 fps) is so amazing. =)
Back to my Point. The person who set up the first Guild Was 2 on Linux with Wine, and the Youtube Video reach for my point of view really high settings and a high resolution with his overclocked CPU. So if you really want play Ǵuild Wars 2 on Linux with higher fps bought a new CPU instead of a GPU.
Hopefully there will be more progress on the GPU or threading support.
Additional: Guild Wars 2 did not utilize my Full GPU Power. I have no, really now Core with 100% during playing GW2. And still not nice fps rate. So i am not sure if my Tip helps. Please take attention to the GPU and the CPU if you report your experience with Guild Wars 2 and Linux.