What happens if you also use gsx to unload/load passengers and bags, do those textures stay in memory all through the flight?
They don't, just like all other objects that gets destroyed after use under our control. And GSX objects equals roughly 3-4 AI models, so they don't really take much memory even when they are showing. On top of that, GSX takes ZERO memory from FSX for its own *code*, because it runs externally under the Couatl.exe program, so it has its own separate VAS space.
Or in the virtual cockpit with the exterior and interior textures loaded? Flying between 2 airports pushes me over the limit and I get instant ooms.
The keyword might be "flying between 2 airports". Perhaps all the stuff you have is taking memory ALONG the flight, and that's is not reclaimed. FTX Global, for example, is loaded CONSTANTLY, not just when you are at an airport, and they don't even have any ability to manage its memory, because vector scenery and landclassess are handled entirely by FSX.
I am so tired of chasing these problems and about to just fly default fsx with the pmdg 777
That's the opposite solution: I've show you the EVIDENCE that
1) the most memory-consuming item you have is NOT the airport
AND
2) KIAH takes ONLY 150MB more than default
AND
3) the PMDG777 on a DEFAULT airport (see my test at KAUS ) takes MORE memory than the default 737 at KIAH, making your strategy of using it over a default airport not very useful. Without even counting that default KAUS is way less detailed than default KIAH.
Amd you still don't want to accept the airports are NOT the problem ? Try to switch off FTX Global, instead, and see it it makes any difference.