John:

When memory efficient is set to no, the client will take enough memory from
the server to load the largest folder in the file structure. It is more time
efficient (but not much).  It will not release this memory unless you unload
the NLM.

We just went through this excerise.  We need the memory for operations
during the day so we switched to memory efficient to "yes".  The memory held
by the NLM went from 52mb to 13mb and the time difference was insignificant.
The only workaround I know of is to leave memory efficient "No" and manually
unload and re-load the NLM on a daily basis.

Good luck