I feel like you have a very strong misunderstanding on how OBS and computer graphics in general work. Check our guide for more information here:
https://obsproject.com/wiki/GPU-overload-issues
The reason that something like GFE does not have this issue is that they:
A) Have access to NVFBC, which is direct, on-GPU capture. This is exclusive to NVIDIA and Steam streaming as a capture method. NVIDIA doesn't let anyone else use it.
B) They do not composite (i.e. add different things to your scene with location, sizing, etc.), which means there is no additional load added to the GPU to render a scene before it can be encoded.
The hardware simply cannot handle playing a game in 1080p, upscaled to 2160p, rendering the scene in OBS, and encoding it all at the same time. Saying that OBS is "too inefficient" is not accurate at all here. It is OK if you do not understand how all the technical aspects function, but please don't assign blame where it is not warranted.