I am using the NOD and storing in dictionaries and XRecords. The resultbuffer gets pushed to the XRecord.
I am not really storing specific entity information. It is basically data and can be approximately 75,000 kb in size or even larger depending on the number of objects in the drawing.
I have tried to stay away from using an external xml file due to the headaches of keeping track of its location, duplicating it, renaming it upon saveas command, etc.
However, some tests have shown that I can write the file in about 5 seconds whereas writing it to drawing memory takes upwards of 20 minutes which is a less than ideal time frame.
The specs for the program required that the data be stored in memory, but I think I might push back against that if I cannot get the time lowered.