When CopyOnSave is true, the SaveToFile and SaveToStream methods create a temporary OLE object, compressing redundant data to save space. This compressed copy is then saved to the file or stream. When CopyOnSave is false, the OLE object is saved directly to the file or stream without using a temporary copy to compress redundant information.  

Set CopyOnSave to false when the container holds very large embedded objects and there might not be enough memory to make the temporary copy. The default value is true. 

OleObject 

SaveToFile 

SaveToStream