it's solid... A fast CPU really helps late game... when every turn takes FOREVER..... IF you play marathon... the short games arn't so bad

I am using a 5ghz 2500k..
I've tried using a 2600 non-k downstairs, because it has hyper threading, but that didn't make the turns faster, and it would crash civ 5 sometimes.. IDK if they've fixed that later on and made use of hyper threading.