is there a significant (20%+) performance increase in getting an i3 3220 over a Pentium G2120 paired with a HD 7850 2gb for games like BF3, Planetside 2, etc.
Mostly no difference as both are dual core.now intel another pentium g2130 @ 3.2gh so now there is 100mhz diff between i3.but i3+ hyperthreating have impact on games like battlefield 3,farcry.
No, they are not *** CPUs. Go back 14 years and run a Celeron CPU and come back junior. Both CPUs will do just fine on a budget. This isn't like the old days were you will be banging your head against the desk over how slow the computer is.
Only in very few games where hyper threading is used the i3 will be faster but as a whole I would say you should get the G2120/30 and a spend the remaining money on a better GPU.