>>389840984
Firstly, unactivated lights don't do anything to performance. 
Unactivated meshes also don't do anything to performance. 
The polygon count is from everything so it's going to be inflated from what is actually rendered at any one time.
However: The large file size indicates that they have lots of 4k/8k textures/maps/masks/etc and those consume a fuckton of VRAM, which eats into performance pretty hard. And typically with multi outfits; the hat is a mesh, the shirt is a mesh the shoes are a mesh, the skirt is a mesh, the underwear is a mesh, the gloves are a mesh etc, so for an outfit they'll have like 12 meshes on at once, with like 5-6 materials each with 4k textures, 4k nroamlmaps, high res matcaps and speculars, and just a LOT of crap they can downscale. 
Plus the outfit will have a lot of polygons because it's unoptimised jap gargage, and also they'll overdo it on the physbones and turn it into a lag machine designed for 12 people jap maps. Some people's avatars are like that big booba merino that when loaded in would easily drop my framerate by 10, just by itself.