The STRUCT system utilizes the flexibility of a powerful graphics display system to provide a set of tools for program analysis. These tools allow the analysis of the static program structure and the dynamic execution behaviour of programs within the entire operating system user program environment of the Brown University Graphics System (BUGS). Information is collected and presented in a manner which fully exploits two aspects of this environment. First, the operating system has been developed in a well-structured hierarchical manner following principles laid down by other researchers. Second the programs under analysis have been written in a structured programming language following coding conventions which make available, at the source code level, valuable program control information. This system is currently being used to predict and analyze the performance advantages available through the migration of function between levels of software and between software and firmware within the BUGS.