Depends on if you are experiencing maxed out CPU or GPU. I'd look at task manager and see which one is 100% in games. Certain games lean towards CPU or GPU.
Personally I'd first upgrade to Ryzen. A series is getting very dated and a very bad gaming CPU. Even my core i5 from 6 years ago outperforms it. You will need a new motherboard and DDR4 RAM. A Ryzen 5 CPU is great for gaming or Ryzen 3 on a lower budget. If you already have a graphics card, there is not much point getting the new Ryzen APU as your graphics card will be doing the rendering.
If you upgrade your graphics card to something nice like a GTX 1060 your CPU will bottleneck you in new games. This will cause shuddering gameplay in more intensive games.