Building lighting after adding foliage grass takes forever?


I recently bought a grass-pack from the marketplace and i use it as foliage. However after i have added my grass and i go to build the scene…it takes forever. I had it running all night and it only built 10% och the lighting. I assume that something is wrong and somewhere i’m not doing things right. I haven’t used UE4 for that long so keep in mind that i’m a bit of a noob ^^


Might be that the resolution of the light maps are to big.

Perhaps, how do i change the resolution of the light maps?