Arguably more fascinating is Gears of War 4. There is overhead in the leap to 4K based on the benchmarks, but not a huge amount of it - not compared to Forza, at least. However, The Coalition announced upgrades for the game at E3 including higher resolution textures, higher polygon counts, longer draw distances, upgraded dynamic shadows and improved reflections. It's hard to believe that all of those could be accommodated in the relatively small render time improvement seen here, suggesting that more intensive optimisation for Xbox One X improves upon the raw benchmark result significantly.
And if that's the case, two of the three 900p titles tested here could conceivably attain native 4K resolution upgrades - Title A is just 1ms away from parity with base Xbox One, while Title E is just 2ms off pace, frame-times increasing by around five to six per cent in both cases.