Serialization by SOAP server

I wonder if anyone can help.I have a SOAP web service that seems to
work OK until it has to send large amounts of data (e.g. 2MB). The data
is initially in the form of an array of objects.

I have checked everything I can and so I know that the method called by
the cgi script has finished and has returned the data (within 5
seconds).

For the next few minutes everything hangs, I presume while things are
being serialized, until eventually the http connection times out.

Then, about 10 minutes later I get a whole load of "Cannot encode
'item' element as 'hash'. Will be encoded as 'map' instead" errors in
the http error log, which I presume is either the output of a
"buffered" response OR is the serializer finally doing its job.

Does anyone know what is actually going on during the response part of
SOAP::Transport::HTTP::CGI->dispatch_to()? I can very easily serialize
the data myself but I don't know how to produce the envelope and insert
my own serialized content.

Any help would be gratefully received.

Thanks!!!!