Map size and performance

Are there any restrictions about map size?
If I make a huge map is the whole map loaded at once or is there "reality bubble"?
Does 1m in reality equals to 1m in OMSI?

Nobody has reached a size limit until now. But each extra tile means more time to load editor/game. 300 tiles give about 4min loading time. But you don't get performance problems playing.
1m in reality IS 1m in Omsi.