UE4 has extreme performance design pitfalls that probably still applies optimizations from the last generation since the engine has to work on mobile devices which have comparatively ancient (no bindless, no stateless compute, no multiview, no tiled resources, poor support for cross-lane operations, etc ) functionality to AMD hardware or other desktop hardware including Intel iGPUs. Epic Games do not even care about getting the best performance for consoles anymore since high end UE4 titles struggle a lot them ...
UE4 is straight up crap in terms of both performance and optimization. The only reason why it succeeded compared to the other public options out there was because it could do high end graphics (Unity couldn't do this), good content creation pipeline (CryEngine was clunky and barely had any documentation in this aspect), and had Japanese documentation altogether ...
There's literally no good public options out there that aren't publisher specific like Frostbite 3, id Tech 6+, Snowdrop, and the RE Engine so the least AMD could do is handhold a couple of game publishers who are still interested enough in creating high-end games that tanks their hardware like Square Enix ...
So yeah, UE4 is a bit shitty like most other 3rd party engines, but it's easy to use and that's why it has had success.
If making a high end engine were so easy, not only AMD but also Nvidia (to expand its The Way-blah, blah, blah program) would have done it by now. They simply don't want to get involved in that, they want to keep being hardware manufacturers.
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
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