Actually on the way home I realized it wouldn't likely help CPU restrictions aka: Skyrim and such. Although Fallout 4 has an adaptive shadow distance thing meant to maintain a frame rate in Concord and boston where shadows hit very hard. Seems to work.
Sorry didn't mean the CPU limitation for all games that exhibit resolution higher more performance difference to Pascal vs Vega, bad grammar on my part should have separated the two into paragraphs.
Forza seems to be the only game that is CPU limited on nV hardware, which similarly older DX12 games showed this specifically AMD sponsored titles (Hit Man was notorious for this as well as AOTS, both of them now have been fixed through driver updates), now I don't think its something on AMD's side telling dev's to do something a certain way, its just the way intrinsic shaders are set up, If using intrinsic shaders for AMD hardware and porting them over to nV hardware, its not straight forward, the same/similar shader will abuse draw calls on nV hardware by not using all cores, this comes down to drivers. The hardware in inherently different and this is why code has to be tailored per hardware.
Having said that, I still do expect Vega to make some gains anyhow, but this specific game its not Vega looking good, its more likely Pascal just looking bad by being held back.
Back to resolution changes and performance differences, this has more to do with fillrates (pixel and texture), Vega's fillrates didn't increase from Fiji as much as Pascal's did from Maxwell, raw shader capabilities also didn't increase as much for Vega as Pascal did from Maxwell either % wise. Where Pascal was able to shift the pixel shader bottleneck Vega's bottlenecks shifted towards parts which traditionally increased with the drop of nodes and didn't happen with Vega. This is probably due to the die size being so large and after decoupling all the units, they could only do so much.