I noticed a marked improvement in FPS, even when close to other aircraft and shooting. Haven't tried over London yet, but will shortly. BTW I am running on a min spec system, and with effects on med and pretty much everything but model quality and textures on low, it's very playable.
AMD X2 7550 Dual Core @ 2.5Ghz
3GB DDR2 RAM
nVidia 9800GT w/512MB RAM
Thats right, it's playable on this system. Won't win any beauty pagents, but you can fly and fight.....and die