The Taverna workflow management system is an open source project with a history of widespread adoption within multiple experimental science communities, and a long-term ambition of effectively supporting the evolving need of those communities for complex, data-intensive, service-based experimental pipelines. This short paper describes how the recently overhauled technical architecture of Taverna addresses issues of efficiency, scalability, and extensibility, and presents performance results based on a collection of synthetic workflows, as well as a concrete case study involving a production workflow in the area of cancer research.