Troubleshooting slow IR map

[AlexP]

For whatever reason the IR passes take an incredibly long time in the scene Im currently working on.

What sort of things are known to significantly slow down the IR map?

I am using Forest Pro for a rug, but it was already slow prior to that.

Using a Dome light with HDRI and various other vray planes/spheres for lights.

Any pointers?

[Neilg]

Change reflection depth to 1 & switch off glossy efects. Sometimes i'll use the vmc script to switch off reflections entirely