GPU won’t matter as CPU limitations are likely happening especially with high TLOD and AI traffic. Drop TLOD, and AI traffic (all types) density down to relieve CPU mainthread limited situations. Even with a 4090 you still have the same CPU mainthread limited situations as everyone else. The new version 1.10 now has options to disable some things like animations, static aircraft and passengers and interior objects. I have a 3090 and have managed to get acceptable performance with TLOD set to 140 (keeps Manhattan detail at bay), FSLTL with IFR 45, static 2, radius 60, all other in sim traffic (airport vehicles, workers, roads etc set to 10%). I’m also currently running DX12 with DLSS2 (but be careful as DLSS loads CPU a bit). not sure about DLSS3.
The problems seen with this lovely airport are not relating to the airport so much as it’s location next to JFK, KLGA, and Manhattan so use your TLOD wisely.
BTW does anyone know how the new airport options will be handled by in game marketplace? I see a potential future issue there as I haven’t seen airport options implemented in game before. So potentially a lot more people will be complaining about performance when it gets released there.