Systems and methods for real-time efficiency and aircraft performance monitoring and delta efficiency calculations between various user- or system-selected phases of flight by determining an efficiency messaging index that gets translated into a messaging profile. That messaging profile is then used to obtain necessary flight and other information from multiple sources. The efficiency calculations and deltas can be used to determine real-time or post-processed benefits, which can then be used to optimize flight(s). Additionally, data is post-processed, which allows the calculation, storage and subsequent usage of efficiency coefficients to enhance the accuracy of the efficiency calculations. There are a number of ways to implement the architecture and order of processing.