Update 1.12.13.0 has been an FPS killer

you not wonder about the “Very High Power comsume” ?

go into the detail page an choose the correct graphics engine ( not only the 3D engine is important !)… then you will see the 100% load.

EDIT: here I explained it and linked an article
https://forums.flightsimulator.com/t/100-gpu-load-main-menu-because-background-hangar-rendering/339365/8?u=michamma