Well I put an AMD FX 8350 ( 8 core 4ghz cpu, but overclocked to 4.4ghz right now ) into my pc a long with a Gainward GTX 660 golden sample 2gb GPU, not exactly top of the line but both juicy enough to squeeze something out of any modern game.
I've messed about with some settings in and out of game and my game is running with most settings maxed without any lag whatsoever and without that lame unit stuttering. When your units stutter and you don't have an fps issue it means your cpu is being bottlenecked by this piss poor optimized engine. I had it at first until I turned Unit Details down and turned shadows down too, both of these are cpu bound thus these are huge culprits when it comes to bottlenecking your cpu in huge battles.
Unit Details setting gives you more varied soldiers the higher the setting, which according to other peoples and my own experience is most definitely CPU bound, making double, triple or even more work for the cpu when it has to deal with multiple variations of soldiers in each unit. Shadows also, I knocked these down to one of the lower settings and noticed I could have way more soldiers on the battlefield without that lame unit stuttering whilst the FPS remains smooth and high, meaning my CPU isn't being bottlenecked by this piece of shit.
Last but not least I am using the SweetFX GEM shader mod from the TWC forum, I think the guys name is lucifer something but I downloaded his shaders etc, tweaked them a bit and my game looks A LOT better, it includes methods to add AA ( the games AA is broken as fuck turn it off ) and also gaussian blur, which if tweaked right makes the game a lot softer on the eyes and all the colours look a lot nicer IMO.
I don't use any of the tick box options like SSAO and distortion etc atm but I'll be testing with them soon.
EDIT: Also in Task manager ( ctrl alt delete ) in processes tab, right click Rome2.exe, go to priority and set it to high, for those that dont already know.
EDIT 2: This is a screenshot from my game just to show how it looks, I've already tweaked more since this picture as the gaussian blur was too strong for my liking and I've also made the colours nicer ( imo ) and sharpened the picture up a bit, though seemingly a screenshot doesn't do it justice still, looks better as I'm playing it, maybe the movement covers up the small crappy parts I can pick up on in a screenshot lol. Still, it looks a lot better than what the game did without using this SweetFX GEM shader.