I’ve also noticed the main menu being very laggy and there being a loss of FPS as well. Like flying though, it will usually resolve itself after a couple minutes, but sometimes it will go back to being laggy again. I don’t really care that much about the main menu though since I really need the high FPS during flights, but it’s still strange and something that seems like a recent issue.
However, my last handful of flights, a few of which have been flown into larger and handcrafted airports, have been fine and I’ve experienced no FPS drops or stutters, thankfully.