Emerging application domains such as interactive vision, animation, and multimedia collaboration need specialized runtime systems that provide support mechanisms to enable plumbing, cross module data transfer, buffer management, synchronization and so on. Using Stampede, a cluster programming system that is designed to meet the requirements of such applications, we quantify the performance of such mechanisms. We have developed a timing infrastructure that helps tease out the time spent by an application in different layers of software, viz., the main algorithmic component, the support mechanisms, and the raw messaging. Several interesting insights have surfaced from this study. First, memory allocation does not take up a significant amount of the execution time despite the interactive and dynamic nature of the application domain. Second, the Stampede runtime adds a minimal overhead over raw messaging for structuring such applications. Third, the results suggest that the thread scheduler on Linux may be more responsive than the one on Solaris. Fourth, the messaging layer spends quite a bit of time in synchronization operations. Perhaps the most interesting result of this study is that general-purpose operating systems such as Linux and Solaris are quite adequate to meet the requirements of emerging dynamic interactive stream-oriented applications.