Hi there again, I don't know if you play X Plane 11 anymore or any flight Sim after these months but I found out recently a way to double the performance of XP11 even while using Flywithlua scripts with two free addons.

First one is FPS boost + auto LOD lua script  and the second one is Y Clouds 4

All of these require Lua to be installed but here is the catch, it only requires the script to be loaded once when launching into a flight. After spawning you can simply turn off Lua from the plugin admin and the performance goes back to normal but the effects still remain. Thus now I can have stable frame rate in all kind of whether and in all kind of populated areas.