GNaniteProgrammableRasterShadows Makes much poor Preformance

Hey,I am using Unreal Engine 5 to make the foliage using the Nanite.I found a action that affect Performance very much.The cmd command is r.Nanite.ProgrammableRaster.Shadows,which the default value is set to 1;I don`t know is this suitable for Artist;

Here`s my Scene using Foliage With Nanite:

Before Disable the r.Nanite.ProgrammableRaster.Shadows,the GPU Profile Showing this,which you could see the Nanite::CullRasterize takes too much GPU Time,Seems the Hardware and software Rasterizer is the issue:

After i disable the ProgrammableRaster,the GPU Profile seems normal:

Could someone tell me the usage of this GNaniteProgrammableRasterShadows and why it been set to enable?