Hello, IIRC you were a bit pensive about how the new lighting was gonna affect performance, so I tried it out on my old potato of a laptop.
I can't compare with previous builds since I didn't save any from past Demo Days and I don't see any on your page, but it's sadly unplayable; 20 fps in the starting corridor and all the way down to 8-10 once any actual fighting starts.
For comparison, the same machine can run Risk of Rain 2 at a barely-playable 20 FPS even when lots of enemies show up.