We've often talked about performance and optimizations here. Some we do ourselves, where we write our own workarounds and submit them back to EPIC.
The best though is when EPIC gives us a fresh release of their engine which has a ton of optimizations, or NVIDIA/AMD optimizes drivers for Unreal Engine 4 since it's so new and as so many of you have experienced.
The super-best is joint efforts between all these parties, developers, hardware manufacturers and janitors to make the world a better place and this is one of these days.
Today we are running the previous "latest" version of Unreal Engine 4 which is a beast of an engine. It's so next-gen it next-genned the next gen and when they give us gifts, we receive them gladly.
As a Producer, I don't understand half of what it's then so I suggest you head over there and read up on all the stuff. We will be integrating this update over the next month, so we have the latest hotfixes from EPIC as well. It's also considerable effort for us so you will see delay in features. Mainly my personal Titan.
I hope you are as happy as we are that UE 4.11 is finally out and just to highlight to you some sexy things in case you don't want to head over and read; Parallelization, improved threading architecture, multicore scaling, command buffers, maximum parallelism, utilize all available cores, faster garbage collection, multi-threaded animation, mark and destroy phases are more cache-coherent, additive animation 'baking' (cookies?), physically based shading model for realistic hair, major improvements to the Hierarchical Level-of-Detail, Circle DoF, LOD BONER REDUCTION TOOL!
Oh man, I'm stoked. Thank you EPIC, you are ... uhm epic.
https://www.unrealengine.com/blog/unreal-engine-4-11-released