it would make a pretty big difference. That A10 just can't keep up with anything intel offers (including the haswell I3s). I think your best bet is to either get an I5 4670k, or like a I5 4430 (either go unlocked or go cheap, the stuff between is meh). If you want stick with AMD the 8320/8350 cpus seem to work as well as the I5s on bf4.
You have an APU. Definitely not an ideal processing unit in a rig with a discrete GPU.
how much of a difference on performance ?
Well with an i5-2500K or better(let alone an i7)... a lot! The awesome power of Sandy, Ivy and Haswell Intel CPU's is pretty much "common knowledge", I would think...