Based on my observations, there appears to be a LOT OF UPDATING in the IRay Resource folder (in the Temp directory) occurring. I assume that has a negative impact on performance, especially on larger projects.

STEPS AND OBERVATIONS:

1) Launch iClone - The IRayResource folder already appears, with a couple default files
2) Turn Preview Auto-update OFF
3) Open a project - All the textures get written to the IRayResource folder
4) Modify ONE texture...
4a) It updates the texture in the IRayResource "live" in sync with the iClone screen, even though you have Auto-update set to OFF
4b) It updates **ALL** textures! Not just all the textures for the item you changed, but the "Date Modified" time changes for all textures on ALL PARTS.
5) Without making any more changes, when you launch the Iray Preview, it will once again "update" **ALL** textures in the iRayResource folder, even though you have made no changes.
6) It will also do a similar update when you do a "Save MI scene" action


SUGGESTION:
A) In short, only write to, and update, the IRayResource folder when necessary.
... for example...
B) Only populate the IRayResource when you do the first "Iray action" - whether it is Preview or "Save MI Scene"
C) If you have Preview Auto-update = OFF, then do not update the IRayResources file until the user wants to update the Preview screen (or do a Save MI Scene)

Larger projects can easily have HUNDREDS of JPEG and PNG files. Constantly updating them must impact performance. And doing updates when you're not even using Iray is pointless, and only adds to the pain.

This process needs to be reviewed and updates should only happen when they add value.