Does iRay render in HD with Subdivision?

I tried an iRay render without HD in the figure. Then, I tired it with HD and with the Subdivision turned up to 3. I really couldn't see the difference. So, does iRay render in HD with subdivision? Is there something special I have to do in order to get iRay to render with HD?
Comments
Iray uses the render-time SubD setting, not the plain SubD setting - the latter is used by the display and for export to OBJ.
OH, I missed this little tidbit. I'm so used to Luxrender which requires (plain) SubD at +3 that I've been automatically doing the same for IRay. Of course, this is good news to me because the plain SubD causes the viewport to slow drastically while the render-time SubD does not.