Source : WordNet®

optimise
     v 1: make optimal; get the most out of; use best; "optimize your
          resources" [syn: {optimize}]
     2: modify to achieve maximum efficiency in storage capacity or
        time or cost; "optimize a computer program" [syn: {optimize}]
     3: act as an optimist and take a sunny view of the world [syn:
        {optimize}]

Source : Free On-Line Dictionary of Computing

optimise
     
        To perform {optimisation}.