I'm not saying that you can't get a average FPS of 80-90+ but I'd be surprised if those CPUs wouldn't regularly cause drops to 40-50 in 64p conquest.
It also depends a lot on the map and just the area of the map itself. On St. Quentin Scar by E flag I can get 120+ looking towards the F flag or that general direction. If I turn around and look up towards B I can go down to ~75FPS while standing in the exakt same place and my GPU usage drops to 55%.
On Amiens I get similar drops in some areas.
On Empire's Edge I get ~80FPS while standing up at D flag just looking in towards the map.
Those maps are the worst in my experience. 64 players on Argonne Forest is still completely GPU bound and I don't think I've ever seen it below 100FPS there.
It's just so jarring going from 100+ to around 70 by turning around and I can immediately feel the added mouse lag. For those used to 60FPS this kinda feels like when the game suddenly drops down to about 40FPS, everything just feels sluggish.