Very interesting video by Digital Foundry analysis of Microsoft's Flight Simulator 2020 on PC.
"However, a generational leap in fidelity obvious comes at a cost. On a Ryzen 9 3900X with an RTX 2080 Ti, ultra settings at 4K means frame-rates in 30-40fps territory for most of the time. Variability in frame-rate depends on how close to the ground you are, or how close to the clouds you get. The cloud system, for example, is very heavy on the GPU, while low altitude flying at ultra is more CPU-intensive, to say the least. But fear not, because Flight Simulator scales very well both on the GPU and CPU, based upon various graphics options they offer here."