To reproduce:

* Open "Displacement Comparison" iClone 6 demo project (you may open any other project with props featuring displacement maps)

* Do the Iray render preview (note Light hierarchy initialization is at 0.00 seconds - screenshot 1 )

* Add any Glow map to both planes at the scene (glow strengthen does not matter)

* Do the Iray render preview again (note Light hierarchy initialization went to 82 seconds - screenshot 2)

It looks like displacement maps split glow map lights into multiple sources (at least it seems)...