Thanks again for the very prompt response.
I will get back to the client with your thoughts and see if your suggestions make a difference.
That will be tomorrow now.
I was thinking that because the app has the world to itself so to speak in a VMware guest, and Windows as the guest has got very little to do except
fopen, fclose, fread, malloc, realloc, free, that Windows entered some strange, normally unseen mode where it was doing something sensible
like give the app whatever it needed and not reclaim memory until such time as all free memory was used up, and only used & discarded
remained.
I would guess that only a persistent app, one that never exits (we run for days) and with no resource competition might show this behaviour.
Regards
Steve