I have solved the initial loading issue and now my sim start up in under 3 mins 
Almost everything is working fine…only two problems:
- „Minecraft trees“: But only there, where i had a world update in FS2020! For example i dont have those ugly trees in brazil.
- City lights at night are blinking/shimmering in distance. I don‘t know if that is suppose to be like that.
I think with the upcoming updates the sim will get better and better…