It's not the graphics that are the issue, it's the FPS.
EPW is a game almost 100% based on CPU power, and since it's a Single-Threaded game, it will therefore not run that well on many multi-core CPU's
For example, I have a i7 6700K CPU and I'll have hundreds of FPS when I'm alone somewhere on the map but the moment that I'm in mass, I'm down to 15FPS.
tl;dr: Unless you're going to get a CPU worth 3/4 of your entire computer build, you're at a loss. PW will most likely NEVER be optimized, and it's actually a very very old game engine.
(Any basic new computer now, not even custom built will be able to play PW on max full)
I have an i5 4690 - 3.50ghz and I get the same fps as this soooo, my advice is don't upgrade for any sort of PW gaming only.
CPU's have barely any impact on gaming unless the game uses hyperthreading - which many few games do (GTA5 to mention) - i5 is perfect.
Get a really good GPU tho, i got a geforce gtx 970 about a yr ago when it was new and it's worked really well. I don't see any need to upgrade even when playing games like black desert.