I had some thing strange going on...
I had lots of instances of PRDocument, at one point it reported 88000...
The key to clearing them out appeared to be, re-initializing,
PRMacroExpander,
Inspecting PRMacroExpander default, the #table dictionary of blocks,
those blocks
had temps, with a #context defined, and that context had properties etc...
still it freed up 100Mb...
Keith