Disable Photoshop Screen Update During Script

Here are several things you can do to make the script run faster. First make sure the playback options are set to accelerated. Here is some code from Xbytor

cTID = function(s) { return app.charIDToTypeID(s); };
sTID = function(s) { return app.stringIDToTypeID(s); };

Stdlib = function Stdlib() {};

Stdlib.setActionPlaybackOptions = function(opt, arg) {
  function _ftn() {
    var desc = new ActionDescriptor();
    var ref = new ActionReference();
    ref.putProperty(cTID("Prpr"), cTID("PbkO"));
    ref.putEnumerated(cTID("capp"), cTID("Ordn"), cTID("Trgt"));
    desc.putReference(cTID("null"), ref );
    var pdesc = new ActionDescriptor();
    pdesc.putEnumerated(sTID("performance"), sTID("performance"), sTID(opt));
    if (opt == "pause" && arg != undefined) {
      pdesc.putInteger(sTID("pause"), parseInt(arg));
    }
    desc.putObject(cTID("T "), cTID("PbkO"), pdesc );
    executeAction(cTID("setd"), desc, DialogModes.NO);
  }
  _ftn();
};
Stdlib.setPlaybackAcclerated = function() {
  Stdlib.setActionPlaybackOptions("accelerated");
};
Stdlib.setPlaybackStepByStep = function() {
  Stdlib.setActionPlaybackOptions("stepByStep");
};
Stdlib.setPlaybackPaused = function(delaySec) {
  Stdlib.setActionPlaybackOptions("pause", delaySec);
};

next togglePalettes() to hide the palettes.

And set doc view to as small as it will go. This doesn't help that much so may not be worth the effort.

runMenuItem(  charIDToTypeID("ActP") );// fit on screen
for(var z = 0; z < 17;z++){
     runMenuItem( charIDToTypeID("ZmOt") );
}

But even with all that, working with layers using the scripting API can be slow.