Framerate loss when upgrading monitor?

[XJLanzaro]

How much of a framerate loss in Battlefield 3 should I expect when upgrading from a 1280x1024 monitor to a 1080p monitor? If I get around 50 fps average now, what would I get when I upgrade, using the same graphics settings in BF3. I have a Radeon 6950.

 

[Paylasici]

20 - 23 FPS.