I'm about to produce an offline HTML 5 application using cache manifest. At times the application will require quite heavy server communications. I'm interested in creating a WCF service for providing the data, but my experience of IIS hosted WCF services verses self hosted WCF services is that self hosted are faster to start up, which is one of the key performance measures for this product. Also where self hosted are single process multi threaded versus, multi process single threaded in IIS they're better for persisting state over long durations. I maybe wrong about these assumptions, please feel free to correct these assumptions if you believe otherwise.