I have an AMD FX-6300 and an R9 270X and play on medium settings with lowered resolution. When I'm out in the mountains or ocean in JC3 I average about 40 FPS, but in cities, even just medium sized ones, FPS drops to 20. And if explosions happen in those cities, as low as 10 FPS. Your graphics card isnt great so you may have to play on pretty low settings, but I feel that inside of cities you won't see as much of a drop as I do. Your CPU is quite a bit better and most of the lag I assume comes from the countless physical objects and people.