efficient

Adjective

• able to accomplish a purpose; functioning effectively
  • people who will do nothing unless they get something out of it for themselves are often highly effective persons...-G.B.Shaw
    
  • effective personnel
    
  • an efficient secretary
    
  • the efficient cause of the revolution
    

• being effective without wasting time or effort or expense
  • an efficient production manager
    
  • efficient engines save gas