为什么我的背景图像被延迟了

我在Sencha Touch 2.1.1中使用一个项目模板来显示一个状态，一个pic和一些关于用户的详细信息，作为列表中的一个项目。当我加载页面时，我看到加载所有图片的延迟，除了第一张，这大约需要JSONP调用拉取状态的时间。你可以在这里看到

我的模板很简单:

    itemTpl: [
        "<div class='listView people'>",
        "   <tpl if='workforceID != undefined'>",
        "       <tpl if='workforceID == '"phind'" || workforceID == '"NULL'"'>",
        "           <div class='avatar notFound user'></div>",
        "       <tpl else>",
        "     <tpl if='presence != undefined && presence != null && getAvailability(presence) == '"Available'"'><div class='avatar status available' style='background-image: url(https://services.xxx.com/emppics/{workforceID}.jpg);'><span></span></div>",
          "          <tpl elseif='presence != undefined && presence != null && getAvailability(presence) == '"Busy'"'><div class='avatar status busy' style='background-image: url(https://services.xxx.com/emppics/{workforceID}.jpg);'><span></span></div>",
          "          <tpl elseif='presence != undefined && presence != null && getAvailability(presence) == '"Away'"'><div class='avatar status away' style='background-image: url(https://services.xxx.com/emppics/{workforceID}.jpg);'><span></span></div>",
          "          <tpl elseif='presence != undefined && presence != null && getAvailability(presence) == '"Unavailable'"'><div class='avatar status unavailable' style='background-image: url(https://services.xxx.com/emppics/{workforceID}.jpg);'><span><em></em></span></div>",
          "          <tpl elseif='presence != undefined && presence != null && getAvailability(presence) == '"Offline'"'><div class='avatar status offline' style='background-image: url(https://services.xxx.com/emppics/{workforceID}.jpg);'><span></span></div>",
          "          <tpl elseif='presence != undefined && presence != null && getAvailability(presence) == '"Do Not Disturb'"'><div class='avatar status dnd' style='background-image: url(https://services.xxx.com/emppics/{workforceID}.jpg);''><span><em></em></span></div>",
          "     <tpl else>",
          "         <div class='avatar status offline' style='background-image: url(https://services.xxx.com/emppics/{workforceID}.jpg);'><span><em></em></span></div>",
          "     </tpl>",
        "       </tpl>",
        "   </tpl>",
        "   <ul class='data'>",
        "      <li><h3><strong>{fullName}</strong></h3></li>",
        "      <tpl if='title != undefined && title != null'><li><span class='"userTitle'">{title}</span></li></tpl>",
        "      <tpl if='roomNumber != undefined && roomNumber != null && roomNumber != '"'"'><li><span class='"userOffice'">Office: {roomNumber}</span></li></tpl>",
        "   </ul>",
        "</div>"
    ]

状态的Ajax调用是这样的:

function getUserPresence (record) {
    var email = record.get('mail');
    if (email && email !== 'NULL') { // Need to actually check for text value of NULL :(
        // Get Users' Presence
        Ext.data.JsonP.request({
            url: Global.presenceUrl + encodeURIComponent(email),
            callbackKey: 'callback',
            disableCaching: false,
            success: function (result, request) {
                if (result) {
                    var presence = result.Availability;
                    record.set('presence', presence);
                }
            },
            failure: function () {
                console.log('Unable to obtain Lync presence at this time');
            },
            timeout: 15000, //if no response something is wrong and just cancel
            scope: this
        });
    }
}

如果我拉JSONP调用，课程的图片立即加载，所以我不确定为什么JSONP调用阻止了背景图像的加载。难道浏览器不应该不管进行JSONP调用需要多长时间都去获取图像吗?