The performance of a Web service is primarily dependent on the design and implementation of its SOAP toolkit. SOAP is widely implemented using HTTP as the transport protocol and XML as the data format. In earlier work we showed that the conversion of data types to ASCII format, required by XML, is a primary bottleneck when scientific data needs to be sent via SOAP. The conversion to ASCII format also expands the message size by a factor of four to ten. This increased size of the serialized format requires large memory buffers