why scrollEnd is after 400ms

Hi,
I make a test on the example for probe. ScrollEnd is detected after 400ms, is it possible to make it faster ?
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=0, minimum-scale=1.0, maximum-scale=1.0">

<title>iScroll demo: probe</title>

<script src="http://lab.cubiq.org/iscroll5/build/iscroll-probe.js"></script>

<script type="text/javascript">

var myScroll;
var position;
var now = Date.now();
var _now = now; 

function updatePosition () {
    dt = Date.now() - _now;
    _now = Date.now();
    position.innerHTML = dt;

}

function loaded () {
    position = document.getElementById('position');

    myScroll = new IScroll('#wrapper', { probeType: 3, mouseWheel: true });

    myScroll.on('scroll', updatePosition);
    myScroll.on('scrollEnd', updatePosition);
}

document.addEventListener('touchmove', function (e) { e.preventDefault(); }, false);

</script>

<style type="text/css">
* {
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}

html {
    -ms-touch-action: none;
}

body,ul,li {
    padding: 0;
    margin: 0;
    border: 0;
}

body {
    font-size: 12px;
    font-family: ubuntu, helvetica, arial;
    overflow: hidden; /* this is important to prevent the whole page to bounce */
}

#wrapper {
    position: absolute;
    z-index: 1;
    top: 0;
    bottom: 0;
    left: 0;
    width: 50%;
    background: #ccc;
    overflow: hidden;
}

#scroller {
    position: absolute;
    z-index: 1;
    -webkit-tap-highlight-color: rgba(0,0,0,0);
    width: 100%;
    -webkit-transform: translateZ(0);
    -moz-transform: translateZ(0);
    -ms-transform: translateZ(0);
    -o-transform: translateZ(0);
    transform: translateZ(0);
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
    -webkit-text-size-adjust: none;
    -moz-text-size-adjust: none;
    -ms-text-size-adjust: none;
    -o-text-size-adjust: none;
    text-size-adjust: none;
}

#scroller ul {
    list-style: none;
    padding: 0;
    margin: 0;
    width: 100%;
    text-align: left;
}

#scroller li {
    padding: 0 10px;
    height: 40px;
    line-height: 40px;
    border-bottom: 1px solid #ccc;
    border-top: 1px solid #fff;
    background-color: #fafafa;
    font-size: 14px;
}

#monitor {
    position: absolute;
    left: 51%;
}

</style>
</head>
<body onload="loaded()">

<div id="monitor">Delta Time : <strong id="position">0</strong></div>

<div id="wrapper">
    <div id="scroller">
        <ul>
            <li>Pretty row 1</li>
            <li>Pretty row 2</li>
            <li>Pretty row 3</li>
            <li>Pretty row 4</li>
            <li>Pretty row 5</li>
            <li>Pretty row 6</li>
            <li>Pretty row 7</li>
            <li>Pretty row 8</li>
            <li>Pretty row 9</li>
            <li>Pretty row 10</li>
            <li>Pretty row 11</li>
            <li>Pretty row 12</li>
            <li>Pretty row 13</li>
            <li>Pretty row 14</li>
            <li>Pretty row 15</li>
            <li>Pretty row 16</li>
            <li>Pretty row 17</li>
            <li>Pretty row 18</li>
            <li>Pretty row 19</li>
            <li>Pretty row 20</li>
            <li>Pretty row 21</li>
            <li>Pretty row 22</li>
            <li>Pretty row 23</li>
            <li>Pretty row 24</li>
            <li>Pretty row 25</li>
            <li>Pretty row 26</li>
            <li>Pretty row 27</li>
            <li>Pretty row 28</li>
            <li>Pretty row 29</li>
            <li>Pretty row 30</li>
            <li>Pretty row 31</li>
            <li>Pretty row 32</li>
            <li>Pretty row 33</li>
            <li>Pretty row 34</li>
            <li>Pretty row 35</li>
            <li>Pretty row 36</li>
            <li>Pretty row 37</li>
            <li>Pretty row 38</li>
            <li>Pretty row 39</li>
            <li>Pretty row 40</li>
            <li>Pretty row 41</li>
            <li>Pretty row 42</li>
            <li>Pretty row 43</li>
            <li>Pretty row 44</li>
            <li>Pretty row 45</li>
            <li>Pretty row 46</li>
            <li>Pretty row 47</li>
            <li>Pretty row 48</li>
            <li>Pretty row 49</li>
            <li>Pretty row 50</li>
        </ul>
    </div>
</div>

</body>
</html>
cubiq / iscroll

why scrollEnd is after 400ms #1057
