This paper describes the results of a study that identified opportunities for worst-case execution time reduction in the Operational Flight Program (OFP) software of BAE Systems’ Hawk Mission Computer. The RapiTime toolset was used to provide the execution time analysis information required to target optimizations where they would be most effective. Potential optimizations were identified for worst-case hotspots at three levels: design level, sub-program level and low-level. These hotspots accounted for only 1.2% of the lines of code but contributed 29% of the overall execution time. Focused optimizations on these hotspots resulted in a 23% reduction of the overall execution time for the analysed code.