When I talked about some of the enhancements in Orcas, I left out a performance improvement for services that use a large number of known types. There are various ways of defining the known types for a service operation, and all of the known type collections are aggregated together for use the first time that an unknown type needs to become a known type. The performance of that first call grew increasingly worse rather quickly as the number of known types increased, although the performance of successive calls was not affected.

This slowdown was fixed in Orcas (you don't need Orcas SP1 to get it). If you are seeing a pattern of slow first calls that is improved by not declaring known types, then you may want to see if installing Orcas makes your first call faster.

Next time: Common Setup Tasks