A method is complementary to processing a retrieve and process pipe specification. The pipe specification is characterized by at least one constituent pipe, each constituent pipe being characterized by at least one of a group consisting of an input node and an output node. The input node is configured to input data, such as a syndication data feed or other data accessible via a web service and the output node is configured to output data, such as a syndication data feed. At least one of the constituent pipes includes a module configured to retrieve data via a web service, such as a source syndication data feed. The wires are configured according to the retrieve and process pipe specification. An amount of time to process the pipe specification is estimated, including an amount of time to retrieve data via the web services as specified in the pipe specification. Based at least in part on the estimated amount of time, appropriate supplemental content is determined to present to a user while the pipe specification is being actually processed.