How can I measure the execution time of a Photoshop Action?

I did not post my action timer script because Adobe design in an intentional bug in Photoshop CC 2015.5 Scripting.  It one thing to let a bug out  unknowingly I do not why Adobe did it.   The reason the posted was it bad to remove metadata like copyright information.  Yet Photoshop save for web does that by default.  I do not do that I try to remove my metadata however, Adobe scripting will no longer set a metadata files to empty its default state.  I can use Photoshop Adobe File Info  to set Copyright data to anything that I want it does not make the image mine nor does Copyright info protect  anyone's image the Law  and the courts do that. I get around Adobe bug by adding Garbage in every document I edit info metadata field using Adobe Script event manager.  So all my run twice scripts will work in CC 2015.5 and CC 2017.

It will add a little over a second to your actions play time.

So here my script if it does not work for you its Adobe's bug not my code.

/* =============================================================================================
// 2010  John J. McAssey (JJMack)  http://www.mouseprints.net/
//  
// This script is supplied as is. It is provided as freeware. 
// The author accepts no liability for any problems arising from its use.
//
// This script is designed to be used by a Photoshop Action twice
// A good pratice to use when creating an actions that use this scipt is for the action 
// not to do a save or play some other action between its two useages of this Script.
// 
// The first time this script is used by an action the currend date and time 
// are saved into the document's meta-data Info Instructions field.
//
// The second time this script used by the action this script retreives the date and time 
// that was saved in the meta-data during the first usage.
// The script Outputs an Action duration message to Alerts the user of the time it took.
// Logs the Action Times into the ActionTime.log file in the folder where the script resides.
// Then the saved date and time is removed from the document's meta-data Info Instructions field.
//
// ============================================================================================== */
/*
<javascriptresource>
<about>$$$/JavaScripts/ActionTime/About=JJMack's ActionTime^r^rCopyright 2010 Mouseprints.^r^rRun twice script utility for action.^rNOTE:Don't play other actions between runs!^r^rFirst Run records Actions Start Time.^rSecond Run removes start time recording and outputs an execution time message.</about>
<enableinfo>true</enableinfo>
<category>JJMack's Action Run Twice Utility</category>
</javascriptresource>
*/
if (app.documents.length > 0) { // LOGFile faild trying this --> app.activeDocument.suspendHistory('ActionTime','main()'); 
  if (app.activeDocument.info.instructions.indexOf("<ActionTime>") == -1 ){ // no footprint fisrt useage 
  //alert("first");
  // Retreive Date Time for Foot Print
  var stime = new Date().getTime();
  //alert("Time = " + stime );
  StartTime = timeStamp() ;
  // put footprint in metadata info instructions
  app.activeDocument.info.instructions = app.activeDocument.info.instructions + "<ActionTime>" + StartTime + "</ActionTime>" + "<ClockTime>" + stime + "</ClockTime>"; 
  //alert( "Saved ="  + "<ActionTime>" + StartTime + "</ActionTime>"+ "<ClockTime>" + stime + "</ClockTime>"); 
  } 
  else { 
  //alert("second");
  var etime = new Date().getTime();
  //alert("Time = " + etime );
  EndTime = timeStamp();
  // Retreive saved information
  ActionTimeOffset = app.activeDocument.info.instructions.indexOf("<ActionTime>") + "<ActionTime>".length;
  ActionTimeLength = app.activeDocument.info.instructions.indexOf("</ActionTime") -ActionTimeOffset;
  StartTime = app.activeDocument.info.instructions.substr(ActionTimeOffset, ActionTimeLength);
  ClockTimeOffset = app.activeDocument.info.instructions.indexOf("<ClockTime>") + "<ClockTime>".length;
  ClockTimeLength = app.activeDocument.info.instructions.indexOf("</ClockTime") -ClockTimeOffset;
  stime = app.activeDocument.info.instructions.substr(ClockTimeOffset, ClockTimeLength);
                duration = ((etime - stime)/1000);
  alert("ActionTime \rStart = " + StartTime  + " \rEnd   = " +  EndTime + " \rTime = " +  duration + " Seconds");
  // Log Edit Session into Log File
  var scriptLocation = findScript()+ "0";
                var LOGFilePath = scriptLocation.slice(0,-4) + "log";
                var LOGFile = File(LOGFilePath);
  writeLOG(app.activeDocument.name + " Start=" + StartTime  + " End=" +  EndTime + " Time=" +  duration + " Seconds\r")
  // End log File
  // Remove footprint from metadata info instructions
  before = app.activeDocument.info.instructions.substr(0,app.activeDocument.info.instructions.indexOf("<ActionTime>"));
  afterOffset = app.activeDocument.info.instructions.indexOf("</ClockTime>") + "</ClockTime>".length;
  after = app.activeDocument.info.instructions.substr(afterOffset, app.activeDocument.info.instructions.length - afterOffset);
  //alert ("before = " + before + " after = " + after);
  app.activeDocument.info.instructions = before + after;
  }
}
else { alert("You must have at least one open document to run this script!"); } 
///////////////////////////////////////////////////////////////////////////////
//       main function
///////////////////////////////////////////////////////////////////////////////
function main(){
}
///////////////////////////////////////////////////////////////////////////////
// END - main function
///////////////////////////////////////////////////////////////////////////////
function timeStamp(){
  // Get the time and format it
  var digital = new Date();
  var hours = digital.getHours();
  var minutes = digital.getMinutes();
  var seconds = digital.getSeconds();
  var amOrPm = "AM";
  if (hours > 11) amOrPm = "PM";
  if (hours > 12) hours = hours - 12;
  if (hours == 0) hours = 12;
  if (minutes <= 9) minutes = "0" + minutes;
  if (seconds <= 9) seconds = "0" + seconds;
  // Get the date and format it
  var date = new Date();
  var d  = date.getDate();
  var day = (d < 10) ? '0' + d : d;
  var m = date.getMonth() + 1;
  var month = (m < 10) ? '0' + m : m;
  var yy = date.getYear();
  var year = (yy < 1000) ? yy + 1900 : yy;
  // create a variable with the fully formatted the time and date
  // todaysDate = hours + ":" + minutes + ":" + seconds + " " + amOrPm + " - " + day + "/" + month + "/" + year;
  // todaysDate = hours + ":" + minutes + ":" + seconds + " " + amOrPm + " - " + month + "/" + day + "/" + year;
  MonthNames = new Array("January","February","March","April","May","June","July","August","September","October","November","December");
  todaysDate = hours + ":" + minutes + ":" + seconds + " " + amOrPm + " " + MonthNames[date.getMonth()] + " " + date.getDate() + ", " + year;
        return todaysDate;
}
// Find the location where this script resides
function findScript() {
  var where = "";
  try {
  FORCEERROR = FORCERRROR;
  }
  catch(err) {
  // alert(err.fileName);
  // alert(File(err.fileName).exists);
  where = File(err.fileName);
  }
  return where;
}
// Write LOG file
    function writeLOG(log) {
        try {
            if(LOGFile.exists) {
                LOGFile.open ("e");
                LOGFile.seek (0,2);      // Move to EOF
            } else {
            LOGFile.open ("w");          // Add unicode marker if we change to LOG file format for this log file
        }
        LOGFile.encoding = "UTF8"; // set UTF8
        LOGFile.write(log);
        LOGFile.close();
        } catch (e) {
            alert(e);
        } finally {
        }
        return;
    }

.