I get much higher minimum FPS using an i7 4790 (4Core with Hyperthreading) than I did with an i5 4670k. Character rendering in highly populated areas seems to be able to use Hyperthreading. On my i5 it would max out a single core for those resources and then limit FPS to like 35-40.

I've run with an i7 3930k and it used as many Cores as I could throw at. So I wouldn't recommend anything less than an i5 2500