XML source size vs . XSLT performance

I have a perl application that calls two
stored procs, each returning multiple result sets.  Currently I
concatenate the multiple result sets from each stored proc into one
xml document.  Worst case the xml document can get up to 300k in size
(when both results from each stored proc are concatenated).
Currently, I'm using Xalan to run a stylesheet on that document but
I'm wondering if 300k is too big of an xml document for Xalan to
transform.  So, my question is should I break it up into two parts
(two xml documents one from each stored proc call) or are there any
limitations with xslt and the size of an xml source document in
relation to performance?

Thanks.