The memory system of a modern embedded processor con- sumes a large fraction of total system energy. We explore a range of different configuration options and show that a reconfigurable design can make better use of the resources available to it than any fixed implementation, and provide large improvements in both performance and energy con- sumption. Reconfigurability becomes increasingly useful as resources become more constrained, so is particularly rele- vant in the embedded space. For an optimised architectural configuration, we show that a configurable cache system performs an average of 20% (maximum 70%) better than the best fixed implementation when two programs are competing for the same resources, and reduces cache miss rate by an average of 70% (maximum 90%). We then present a case study of AES encryption and decryption, and find that a custom memory configuration can almost double performance, with further benefits being achieved by specialising the task of each core when parallelising the program.