It seems Nitrogen requiere a dedicated section at this forum, we are many people asking about this great editor xD
By now, I have played a 8192x8192 size map with a friend, tha last screenshot I shared here, with ultra size cities, lots of citites, countrys, rednecks, POIs, etc.
The result: An "old generation" i7 16Gb RAM 2Gb NVidia get out of RAM many times, with about 1 hour playing. However a "young generation" i7 16Gb RAM 2GB Nvidia works well with graphics at medium, so I think this is the minimun requirement for such a map.
I really love this game 😛