I was once told by a tech at Poser that if you have a big render job you can restart in "diagnostic startup" mode and it will free a lot of memory and improve render speed.   Run>msconfig>check "diagnostic startup" and restart, run Poser and render your file.  It has helped me in a few instances.  Supposedly, it does a minimal load and could be a simpler way to unload all the things previously discussed.