Recent versions handle real-time global illumination (Lumen) and dynamically render geometry to insane levels of detail (nanite). Both of these are groundbreaking achievements. But having had to install this in a bunch of university computers I can tell you that it comes at a cost.
Interestingly, the most significant issue is the space these installations require. We have optimized our installation as much as we can, but we nonetheless had to introduce systems whereby local storage was wiped clean every two weeks.