All different techniques. Don't know why you bring up Christmas, but don't care. Who knows what kinds of optimizations Johan Andersson and his team are using in their Frostbyte engine, but they must be significant. We've just seen the first version of SFR in Civ. BE, it works great and should get even better going forward. As for Async and fluidity, I obviously haven't seen the Liquid VR SDK yet, but apparently AMD is using it to reduce movement lag and keep it under the maximum 16-20ms to reduce nausea.