My DX11 modules inject graphics into a DX9 program. They only do so on command and not every frame(it is a render to texture cockpit lighting system). The users who are experiencing this problem are all ATI users and they have given me video and screenshot evidence of the VAS usage of the program climbing as they change light intensity settings (Release is called on the resources within a few seconds of stopping at a particular setting since the program is 32bit and running close to the limits of 32bit VAS space). ClearState has been tried but to no avail. All NVIDIA users don't have this problem however and I ran my own tests which showed a momentary spike in VAS within the limits of what I would expect given the amount of resources I am handling but it drops back down almost immediately after the unloading is complete.
I found through Google that this occurs in several DX11 games on ATI cards as well so its definitely not an isolated issue either.