Tip: If somebody struggles with CPU limited performance, don't forget to optimize DRAM speed (besides OC CPU). TW games seem to be pretty DRAM speed and also latency sensitive. In Attila I could measure up to 40% more frames from just doubling the RAM speed (see my post here:
https://www.twcenter.net/TWC-Total-War-Attila-benchmark-thread). And TW3K seems to like fast RAM too.