This game is weak even my old overclocked gtx960 4gb ran over 60fps easy.
I don't think I would use the word "weak" to define Doom in terms of IQ and performance. The engine is actually really sophisticated, and uses a lot of information from the previous frame to render the current one which really increases performance.. Unreal Engine 4 does this as well, and that's a large part of what makes multi GPU so difficult to implement with these engines.
But for what is presented, Doom is one highly optimized son of a gun. Lots of dynamic lighting, shadows, reflections and particle effects which are done really nicely. In fact, Doom has way more dynamic effects compared to games that use the Frostbite 3 engine like Star Wars Battlefront, which is widely seen as having top notch graphics.