I have done a HUGE job on optimizations. So at this moment it is very possible to have two huge (512x256x512) scans of the world (overworld and nether in this case) next to each other. I also send the data gradually with a cool slide in effect added on top:
https://gfycat.com/gifs/detail/ampleanguishedcormorant
https://gfycat.com/gifs/detail/ampleanguishedcormorant