Sadly not only the Graphicscard is importent. Also the Speed 1 single of your Core CPU can bring. Not to mention the number of object and the number of Different objects
Conserning CPU: This is true... but as I said, I wanted to keep it simple and in my experience the GC has the biggest influence when you have - lets say more than 2.5 GHz.
Conserning objects: This is why I wanted to know about the video memory. If all the data of the different objects and all the geometry of the object instances in the map fit in there, you don't need to load them from main memory to video memory while playing the map. When this happens, the loss of FPS is disproportionately high.
Why do I think that it works this way? I made a map with a forest in it that covered the whole map. Than I started to increase the view distance and Overgrowth draw distance (set them on the same value). What I observed was that at an certain threshold framerates droped signifacantly when I walked around, but went up again when I just moved the mouse around and stood still. I think that this happened because the tree instances that were in my viewradius completly filled the video memory. So when you move, the ones coming into sight have to be loaded from RAM to the graphic card.
My theory is, that modern grafic cards have enough power to draw a LOT of triangles when only using the simple BF2 shaders without dynamic shadows and other expensive effects they have to calculate in todays game renderes. In most cases the limit will be set by the amount of available video memory and not by the computational power of the card.
I haven't done a lot of undergrowth testing yet, but I think it is ideal for getting more detail. First of all it has no collision mesh and therefore does not strain the server. Secondly it only uses small meshes and textures that don't need much memory. But this needs to be checked out more carefully.