[Zope] XML Doc and speed

I've been playing around with the XML Document Product again and I've run into a limitation that I have run into before: large XML documents process slowly. Getting data out of an XML Document is much slower than fetching data from an external relational DB. The trouble is that I have a large number of records that are hierarchically structured. Getting the data into XML is a lot easier than using SQL where the structure of each record demands that each record get spread out over a dozen or so tables. I'm doing this in one large XML file with the children of the root element each representing a record. Would I gain any speed by giving each record a separate XML Document? Thanks, Chris