something i didn't mentioned before was that i tried with all viewport modes. opengl, direct3D, Nitrous and its the same. and that they are ies corona lights
Maru, this is in the viewport navigation, while modeling, etc. it can be wireframe, shaded is the same.
its easy to replicate. create a corona light and assign an ies file and make 800 instances, the view port will become extremely slow to move around.
maybe a possible solution would be to have a checkbox like vraylight to disable the representation of the ies shape in the viewport?
gl