Crash during Light Build

What are your computer specs?

I was building light for my level and of course this usually takes a lot of time. But it was taking even longer tonight; the first 15 minutes my pc was essentially hard locked. 10 more minutes of it being basically useless – I could sort of see the bar progress from 0% to 11% though. Then the Swarm Agent crashed, then Unreal crashed. I do not have a crash log for this saved in my crash report folder.

Usually it takes a while with my larger maps, but this was pretty nuts. It has 670 actors, almost all meshes (like 10 simple brushes in there.) Is there any way I can make the light building process easier on my pc? I’m using a LightmassImportanceVolume set to 2000x2000x2000 even though my whole map is much larger.

Is it crashing due to size? How am I supposed to know when it’s too big? What can I do?

i7 920, 12gb ram, gtx 460, ssd with ~10gb free on average, win7 64bit