[Zope] Growing Refcounts

Hi, invoking a xmlrpc call on any method, for example calling the default index_html dtml method, causes the delta of xmlrpclib.Unmarshaller and xmlrpclib.FastParser to increase without freeing instantes. After testing with diferent Zope versions I have discovered that calling the same method on Zope 2.2.4 works ok. Can anybody report the same problem? Is there a bug in the latest versions? Any solutions?