tnx guys, i have 16 G of ram but I will put inside more, i7 3930K, Is it possible to create chunks of map? I can divide 3 regions? Also I saw degrading geometry, I know what it is but I have never used it neither in max or in UE… I played GTA 5 one two years ago, and I was thinking how does they build such large map on PS3? I saw that buildings far behind are in some fog and they are not visible also character have radius of creating geometry, so sometimes when I drove car very fast, hardware doesnt have time to respond and some geometry is degraded and textures not loaded, anyway I wont drive fast cars on my map, is it possible to implement such thing in my project? I am relatively new in UE so what would you recommend me to start with? I will later need characters and cars (moving realisticly like on street) is there something good on market? @Vollgaser Tnx I will I have no idea what sub level stream is 
maybe something like proxy or xref in max. I am starting this and I will have a lot of questions wait till it come going to read world composition 