Yeah you can try single player and record the fps and share it with us. Btw i have a slower graphics card(hd 8750m with i7 4th gen) and can play bf4 in medium settings with absolutely no lag.
But stay out of the 64player servers. They are extremely cpu hungry. Even my I7 lags a bit when i game on 64 player servers.
If you want a cpu upgrade then you should consider buying an I5 3570
Then for the gpu you should buy an AMD R9 270 or an R7 260x.
Difference-
The r9 270 is faster
The R7 260x its a bit slower in terms of gaming. But it fairs well.(Ps4 and x box one use the same GPU. So its basically a ps4 gpu in a pc)
If you are into gaming then as you may know more cpu hungry games are coming. So buying an fx 6300 is a good choice. It will last you for a couple of years