If you set the resolution to 1280x1024, I bet the game will run very well with most of the new options turned on.
You are asking more of your hardware than the hardware is probably capable of. The specs to run the game do not take into account anyone trying to get thier hardware to run unreasonable resolutions for that specific hardware.
To run the three monitor resolution you want to run, you really should have opted for a 6970 video card.
There may be other things impeding the performance of your computer. If the CPU activity of the computer is at 0 percent (task manager), when nothing is running, then you probably are getting what you can out of it. Did you shutdown any unneccessary services in Windows 7? Did you shut off the Aero desktop?
There are things you can do to get more performance out of your hardware, but there is not much that can be done when you are potentially asking the hardware to perform outside of its performance envelope.
=========================
I have a 4850 video card in my computer at home. From Sapphire, it was overclocked. It only has 512MB of video RAM. My CPU is an E8400 Intel running at 3.6Ghz. My OS is Windows XP. I do not run the Catalyst Control Center. Now, I probably have one of the cleanest running systems in the game, so it will typically run a bit better than another comparable system.
To start off, under Windows 7, with the Catalyst Control Center running and at default clock rates, another 4850 will run about 25% slower than mine system will, given the overhead of Windows 7, a default clock rate card, and running Catalyst Control Center. I mention that as an attempt to give a performance base line.
In the game, I tested with all the options checked in Options->Graphic Detail->Advanced, with the shadow texture size set to 1024. The sliders in Options->Graphic Details are all at the default location. In the "Video Settings" I set one notch of anti-aliasing, the resolution to 1280x1024 and a Maximum Texture Size of 1024. For the purposes of this test I disabled vertical sync.
Using the ndisles terrain and launching a P51D at field 7, my worst case frame rate was 64, while looking at the buildings on the field. When looking anywhere else, it was above 85 and panning was smooth when changing views.
I really do not consider this playable as that frame rate would drop very quickly once in a crowd. Basically I am asking too much of the video card. I compared the specs of your 6950 against my 4850 and my 4850 is somewhat faster than your 6950. Once you toss in the performance loss of your operating system and Catalyst Control Center, I really do not see how your video card is going to be able to run that three monitor resolution at playable frame rates.
When I disable all the options, except "Detailed Terrain", "Detailed Water", "Bump Mapping", and "Local Water reflections" and disable clutter in the Options->Graphic Detail panel, I get frame rates from 169 to 185 at the same location and looking from side to side. Very playable. This is almost exactly what I had with the previous version of the game.
If anyone is successfully running a three monitor configuration, using an ATI 6950, I would like to hear about it.
