The recent popularity of XML and Web services has lead to a surge in models and platforms for distributed XML data management applications. This work investigates performance issues involved in the deployment of the ActiveXML (AXML) platform for such applications. AXML documents are XML documents, part of which is extensional (present in the document), while part is intensional (specified as calls to Web services). Materializing an AXML document thus requires activating all service calls, and gathering the call results in the document.