Got it >.<
Before:
http://www2.pic-upload.de/img/30487272/UE4Editor2016-04-2709-49-32-70.jpg
After:
http://www2.pic-upload.de/img/30487274/UE4Editor2016-04-2709-49-42-92.jpg
If ue4 then loads the chunks, it takes about 2 sexonds to add a 20x20x50 Chunk without any lags (the engine somehow can’t spawn the instances faster than that -.-)
Multithreading would fix that, but not in Blueprint -.-