With my system, I'm getting around 30fps in the cockpit sat on the runway at Heathrow no matter what setting I use. Screen res, low, ultra, whatever, nothing changes the performance. The dev tool indicates "limited by MainThread". Core 0/thread 0 is at around 70-80%, all other cores around 35%. Both CPU and GPU seem to be ticking over compared the how they run when playing other games. The system and GPU RAM is not being fully utilised. It's like the CPU core load is not being balanced correctly and core 0 is limiting performance.
Interesting that the dev tool says that. I pretty much have the same thing where my CPU and GPU are not being utilised. Others have it too. Surely something that will be patched...