Adding a small loop cache to a microprocessor has been shown to reduce average instruction fetch energy for various sets of embedded system applications. With the advent of core-based design, embedded system designers can now tune a loop cache architecture to best match a specific application. We developed an automated simulation environment to find the best loop cache architecture for a given application and technology. Using this environment, we show significant variation in the best architecture for different examples. The results support the need for future fast synthesis of tuned loop cache architectures.