Part of worlds do not load and change rapidly

huge chunks of worlds will either be invisible or rapidly change textures even though registered as one solid block.
I first found it in the new dimension but when I couldn't find the end dungeon or my way out I decided to make a new world where everything was effected.
also I'm not quite sure what it is but in some of the pictures you may be able to see some strange figures which sort of look like ender dragon parts which also may be part of it