Color drops when mouse is moved

Code

var group = new Group();
var array = [];

function createPoint(x, y, radius) {
    var circle = new Path.Circle({
        radius: radius,
        center: [x, y],
        fillColor: 'blue'
    });
    group.addChild(circle);
    array.push(circle);
}
var t = 0;
var currentMousePoint = new Point(view.bounds.width / 2, view.bounds.height / 2);
var currentMouseDelta = new Point(0, 0);

function onMouseMove(event) {
    currentMousePoint = event.point;
    currentMouseDelta = event.delta;
    array.map(function(object, i){
        object.fillColor.hue -= i / (t * 10)
    })
}

function onFrame(event) {
    t += 0.1;
    createPoint(currentMousePoint.x, currentMousePoint.y, 4 + Math.random() * t % 20);
    group.position.x = t % 0.2;
    group.rotate(event.count / t / 200, view.center);
}