FINALLY! The solution for me was to STOP sharing the "root" folder. IBM strongly recommends this never be shared. When this is shared via NetServer, during the Windows pre-fetch ALL file systems are queried.. This includes non-PC files systems - QSYS.LIB, QNTC, even your optical drives. By simply sharing a directory (or most of them) within the system root instead of the root itself, our performace has increased substantially.