Working with large world landscape in editor

I’m actualy working on a 14*14km tiled landscape. To get a better view of what i’m doing (I use a large stamp system to modify a landscape generated in World Machine), I need to load every tiles but this make the editor running at something near 5 fps and this is not very comfortable.
I’ve already generated LODs for every tiles with suitable distance transition giving me almost 60fps while ingame but the editor don’t seam using those LODs. It is possible to use level streaming/LOD transition in editor ? Or do I need to load only few tiles, work on them, then load every other tiles or play the game when I need a preview?

I still need advice on this please.

Bump, Seriously, I experience terrible performance while editing tiled landscapes.

Even when the tiles are hidden, it still tanks performance. Also, saving. SAVING! whenever I try to save more then 3 tiles there’s a chance the editor will crash, or take ages to save.

I have noticed better performance when I load one tile at a time, but this takes hours (not exaggerating)

And, yes I’m running a slightly outdated (graphics wise) machine, but I think 3.0GHz with 16Gs of RAM should do better.