Soryy for the late reply - your post totally escaped my attention. I haven’t found the cause. Activating RRCulling doesn’t do anything. Just did a new test - some objects were added to the scene since my last post though;
Day-GPUlightmass: 667 drawcalls
Day-Lumen: 1035 drawcalls for 5 moveable lights: 1 directional, 1 sky and 3 pointlights
Night-GPUlightmass: 650 drawcalls
Night-Lumen: 2975 drawcalls for 47 moveable lights (insane I know - just for testing Lumen)
As for a CPU bottleneck, I’m on a 5950x and its barely used for 20% in the Night Lumen scene. The rtx3080 is at 99% though.
Hoping 5.2 will come soon with some new improvements for Lumen & VR