The lighting build process

I have some questions about the lighting build process. I’m building the lighting for a small scene with simple geometry and only a handful of lights. Even at “medium” or “preview” the build still takes approximately 30 minutes.

What’s intriguing me is that it takes two or three seconds to jump straight to 96%, then it stays there for the rest of the build time, before going straight to 100% in the last second before it finishes.

Are these two things connected? Is something wrong with my build process?

Do you have a lightmass importance volume covering the level?

Also, what CPU do you have?

No! Good thinking, I forgot all about that.

The CPU is an i5-3450.

Lightmass importance volume can help, so that it doesn’t spend a lot of time in areas that don’t need it, but the processor isn’t super fast either and that’s going to affect lightmass build times. 30 minutes isn’t usually bad, but you should be able to do a full level overnight once you have it finished.

If lightmass importance volume doesnt help either check every mesh’s lightmap resolution to make sure they arent set to abnormal values by mistake(like larger than 2048.)