Improve Neopixel Peformance?

Actually, just ran a test, the framerate is dropping to 12fps when the code is executed - otherwise it runs at 33fps.

//hacks to get TWEEN to work
var window = {};
window.setTimeout = setTimeout;

var TWEEN = require("Tween");
var neopixel = require("neopixel");

//hacks to get TWEEN to work
process.hrtime = null;
TWEEN.now = Date.now;

var lastLoop = new Date();

function animate(time) {
  
    var thisLoop = new Date();
    var fps = 1000 / (thisLoop - lastLoop);
    console.log(fps);
    lastLoop = thisLoop;
  
	TWEEN.update(time);
}
setInterval(animate, 1);

function run() {
  
  var leds = 24;
  var arr = new Uint8ClampedArray(leds*3);
  var n = 0;

  var coords = { x: 0, y: 0 }; // Start at (0, 0)
  var tween = new TWEEN.Tween(coords)
      .to({ x: 255, y: 2000 }, 1000)
    .easing(TWEEN.Easing.Quadratic.Out)
      .onUpdate(function() {
        var r = Math.round(coords.x);
        n = 0;
        for(var a = 0 ; a < arr.length ; a++) {
           arr[n++] = (Math.random() * 255) * 0.25; 
        }
        
        neopixel.write(D30, arr);
      })
      .start();

}