the 3770k wouldn't be too much of an upgrade and would prove to have a very bad increase of performance for the price you pay compared to the performance you got now.
i5-3570k should be MORE than sufficient at handling Radeon 7950 and with that overclock it's even more sufficient. It's pretty obvious if you run 1000 things at a time while gaming that you will expierence slow framerate.
I use a GTX 670 which is more powerful than the Radeon 7950 and I only use an i5-3570 running on stocks speeds and I never see CPU usage of 100% in gaming, which means the CPU isn't bottlenecking. The only thing holding you back in gaming, if you don't use your CPU power for all kinds of other things than gaming, is your GPU.
You can monitor your CPU usage, GPU usage, RAM usage, clock speeds - Everything on screen if you follow this guide and then you can tell if it's your CPU or your GPU that is the current problem - http://www.overclock.net/t/1229915/how-to-cpu-and-gpu-usage-along-with-fps-in-game.