the question is a bit tricky because you are comparing apples and bannas, The point of lumen is to work with nanite. without nanite you get performance drop. Is stated at the link bellow, in the section “Large Worlds”
Lumen does not require Nanite to operate, but Lumen’s scene capturing becomes very slow in scenes with lots of high polygon meshes that have not enabled Nanite. This is especially true in scenes if the assets do not have good LODs set up for them.