Efficiency of communications
Very often, the programmer will have a choice with regard to factors that can affect communications performance. Only a few are mentioned here.
Which implementation for a given model should be used? Using the Message Passing Model as an example, one MPI implementation may be faster on a given hardware platform than another.
What type of communication operations should be used? As mentioned previously, asynchronous communication operations can improve overall program performance.
Network media - some platforms may offer more than one network for communications. Which one is best?