In this paper an ARM big.LITTLE system with Global Task Scheduling is evaluated in terms of its energy efficiency and performance measured in execution time. The big.LITTLE system is evaluated against the same system but with only the big or LITTLE processor active. The evaluation is done by performing experiments that target three different levels of load: full load, varying load and low load. The benchmarking software PARSEC Blackscholes and BBench are used to put the system under a synthetic workload in the tests. The results show that overall big.LITTLE achieves an improvement in execution time for all test scenarios, although very slim for varying load, and is more energy efficient than the big processor with the possible exception of a low load scenario. However, the LITTLE processor by itself is found to be the most energy efficient system even though it showed the slowest execution time.