Best Practice - collection() function

Hi List,

I use the collection function to generate a single FO file for PDF output.
There are several times I use the collection function to output different
information for the FO (table of contents, index). Everything works as
expected, but it becomes highly inefficient when I use the collection
function on the same folder 3 times. 

For example, I would use the collection(file:///c:/folder) 3 times in my
xslt:

* to build a TOC
* to build a Index
* Build chapters in a book.

Because I have to build my FO with page sequences, I end up calling the same
800 xml files 3 times. Is there a way to do this more efficiently?

Just looking for some ideas...

Thanks,

Phil