5.4.2 has this cvar called r.ManyLights. this is a kinda stresstest for it. i’ll not rebuild the map to test it, but you could give it a shot.
if you use lumen… you should avoid loads of emissive lights. they will produce gi noise. they should all be rendered into a custom unlit/emission pass and bloomed seperately. the rectlights should give you some sort of noisy ambience.
just spitballing.