I just want to report in that with my 'medium' system I'm running Cliffs of Dover just fine, without any crashes or stutters and decent framerate ( ~ 30 - 35 or so )
My ingame settings are on normal/high. Everything from shadows,plane details damage ect. on high, but land detail is on normal.
I don't fly over london often as I'm a fighter but over the English coastal airfields and over the German fields in France my game is keeping up good. An increase in FPS is always welcome of course! But people claiming that this game is utterly broken can't be right.