vRO_function_execution_time.js

// To test a function and get back its return
function printElapsedTime(fTest) {
  var StartTime = Date.now(),
      vReturn = fTest(),
      EndTime = Date.now(),
      difference = EndTime-StartTime

  System.log("Elapsed time: "+difference+" milliseconds") //5001 milliseconds
  return vReturn
}

var yourFunctionReturn = printElapsedTime(sort)

function sort(){ // your function
    const array1 = [1, 30, 4, 21, 100000];
    array1.sort();
    System.log(array1);
    System.sleep(5000)
}