performance question

Hi,

I'm using Zeus successfully for more than one year, and I'm very happy
with it. Now I have to deal with XML documents containing embedded PDFs
(base64 encoded), so the documents get pretty large. The time required
for unmarshalling document does not scale with the file size of the XML
document. Some measurements I've taken show these results (taken on a
dual Xeon 2.4 GHz, 1GB RAM):

filesize (bytes), time needed for unmarshalling in msec
112435,		10974
220235,		43908
435835,		125428
743835,		259105

Can anyone give me a hint to reduce the unmarshalling time? Is there a
way to get Zeus scaling better?

Regards,
Stefan