I have noticed that when i fly GA in VR over Ireland, the flight is always very smooth.
As compared to recent flight locations, such as Seattle (near Mount Rainier), Sweden (around Arlanda area) and also south of England, there were stutters but playable. While Ireland was completely smooth !
I’ve got PG on, and i use a gtx 1080, ryzen 53600, 16 gb ram with a quest 2.
My guess would be that there is a lot more barren grass land and a lot less trees in Ireland. It’s the same when you fly in the desert of Arizona, Nevada etc. You get much better performance there as well, because you only get a few shrubs here and there (and less buildings too).
Both Bing and Google maps have problems with sporadic colour changes. Some bright green next to some dark green, trees all over the coast near Connemara, Killarney lakes looking odd etc.
Much newer data needed! ORBX was going to re-do it but there were licensing cost issues I believe. They were horrendous and not viable economically.