I'm not sure on the exact number but I'm getting from around 20-30 or more FPS, however it drops significantly when I'm viewing smoke or fire/artillery effects which leads me as well as others to believe it's because of bad optimization of said effects, not just because of my out dated hardware since I've seen people with GTX whatever expensive ass cards whine about it as well.
I had the same issue with my old PC (significantly worse specs) that I had until late 2014. Whenever there were a lot flames or especially this phosphorus strike from Rifle Company on my screen, it dropped to 1 fps or something.
However with my current specs I don't have any noticeable framedrop anymore in such a case. I think the Radeon 480 is pretty much on same level like the nvidia 1060, but I don't believe it has much to do with the GPU cuz until 2016 I had a very mediocre nvidia 750ti and I did not have any framedrop there as well.