Ah ok. Sorry about that, I'm so used to people asking about RotTR these days. Are you running SSAA 4X? That would essentially be running the game at 16k, which is insane. Dial down to fxaa or no aa at all, and see if that improves it. Also, run Doom in Vulkan instead of OpenGL, it will massively improve performance (see: http://www.pcgamer.com/doom-benchmarks-return-vulkan-vs-opengl/2/)