New processor?
Nobody said you "have" to buy a new processor.
*It's still not clear on whether you are happy with your current FPS in games and just want less frame rate drop when recording or exactly WHY you're thinking about upgrading.
I keep recommending NVidia Shadowplay for recording so maybe you try that if you have not and report on how that works for you.
As for FRAPS I thought you'd suggested you didn't record with that now but tried OBS so it's a bit confusing now...
*as for getting over 45FPS with Ultra whilst recording BF4 on a G3258/GTX750Ti I find that pretty unlikely:
http://www.bit-tech.net/hardware/graphics/2014/02/18/nvidia-geforce-gtx-750-ti-review/5
How is that going to happen when this benchmark says you get 28FPS average with a much better CPU while not even recording?