No need for a new CPU if you don't have the cash. I run an i5 with 6 toons on 4 monitors running ogre/jb and watching videos while playing and I prob get anywhere from 20-40 FPS on my focused window depending on zone. I do have all none focused windows limited to 15 fps. ISBoxer is a powerful tool, use it. My system is an i5 2500k @ 4.5Ghz with 8G RAM at 800Mhz, video is a GTX 760 at default frequency. Your CPU is a beast OC that bitch.
What do you have all the clients options set to? Everyone of mine excluding the tank is set to extreme performance and the tank balanced so I can see spell effects and all casting/trigger animation.