efficient
adjective
ɪˈfɪʃnt 
ɪˈfɪʃnt doing something well and thoroughly with no waste of time, money, or energy
an efficient secretaryefficient heating equipmentthe efficient use of energyWe offer a fast, friendly and efficient service.As we get older, our bodies become less efficient at burning up calories.fuel-efficient cars (= that do not use much fuel)Opposite
inefficient
efficiently ɪˈfɪʃntli ɪˈfɪʃntli 