@erwin23p,
Your CPU is probably not the problem bud. And changing your CPU may be a bit costly since your ivy bridge is a socket 1155. Remember, clock speed is not the main determiner of performance. The architecture of the cpu is the main factor in performance. So after the ivy bridge is the haswell which has just been upgraded with the release of the skylake. Each processor "family" is a different chipset IE motherboard. So, unless you want to replace your mobo along with your cpu, I would stick with what you got. Sadly, your problem is likely your GPU. Most serious gamers these days rock the NVidia 9xx. Ideally a 980, but you can save a few $$$ with a 970 if you are not running resolutions higher than 1080. However, for 2k/4k you should probably opt for a 980 or even 980ti.
However, before you do anything, on multiplayer FPS can be bottlenecked by the server. So, even with a skylake + 980ti you very well may still have crappy frames on "lesser" servers. Hate to recommend you upgrade when it may not make a difference. Try some other severs / less populated servers to test.
just my two cents. Good luck!