@ruidx That hair has 1971072 polygons... Simple. I don't think that with the "decimator" plugin you will earn much. In Rhino , at 50% reduction, it still keeps 900 thousand... Try "Dsf Tools", reduce in Blender or Rhino, and create a new dsf.
Besides, it is full of alpha channel in its textures. Try to compress them. they are in C:\My DAZ 3D Library\Runtime\Textures\Linday\Classic Blowout Hair. Some reach 5Mb...
All that, added to Iray's slowness..., can become vomiting.
