Actually in 2017 you should be able to make big scenes with fully dynamic lighting, dynamic GI, large scale AO, soft shadows, POM, Tessellation, Volumetric lighting, volumetric fog, volumetric clouds etc. and happily dance while looking at something beyond 60 frames on mid range hardware. Most of these features were in other engines way before 2017 as well.
Edit: The performance problems with UE4 mostly is because nobody really knows why things run so slow, you look at the code and it’s flawless, you compare the same feature with other engine it’s probably 3 times heavier. But since the code looks flawless that performance difference is accepted without question.
Like the tessellation problem, it’s been around since UE4’s existence and still engineers don’t really know why ~4000 tris would cost around at least 5ms to render. While in other engine like frostbite’s battlefront even the rocks and trees are tessellated, let alone the landscape.