Delta S Performance Guiding your energy towards brain recovery and better performance. What is Delta S Performance? Delta S Performance is a Functional Neurology and Sports Medicine Clinic with the mission of guiding your energy towards brain recovery in order to achieve success in all aspects of life. We take our inspiration and mindset from the scientific term Delta S (ΔS). Often referred to as entropy, this theory proposes that left alone, all things go toward disorder and dysfunction. Energy needs to be applied to create order and function. This holds true for our health, as well.