Problem with big world in worldcomposition mode, crashing editor.

Hello, i made a tiled world from an actual island, with the size og 50425x50425 in 625 tiles with the resolution og 2017x2017.
I have no problems with smaller projects but when i import this size landscape unreal crashes when i try to load the levels, i can load som of them but if i try to load over 50-100 tiles the editor crash.
Is there some tricks to make big worlds without the editor losing performance.
Can i load only some tiles at a time in the editor?
Hope someone know what im talking about.

Make use of streaming layers as well as hide the layers and tiles that you are not using.