FPS decreases with increasing altitude past FL250, clear weather, any aircraft with a clean X11, I’ve even tested it with sliders all the way down and it still happens, it’s been happening since X11 1.30 (And current X11.40b6).
I’ve tried everything, other users in the Zibo mod forum have confirmed this same behaviour when passing between FL250-FL300+ onwards, tested with multiple aircrafts.
What is causing this odd behaviour?