MapXtreme+Asp.net 动态轨迹（请求大神指点）

功能简介：在MapXtreme+Asp.net的环境下实现轨迹回放功能，经过两天的努力基本实现此功能。但还有部分问题需要解决，求大神们指点迷津，问题会在结尾处提出。

客户端前台页面

<asp:ScriptManager ID="ScriptManager1" runat="server" />
        
        <%--该js方法写在scriptmanager之后，防止出现Sys未定义错误--%>
        <script type="text/javascript">
        //获取pagerequestmanager实例后添加事件
        //在因同步回发或因异步回发而刷新页面上所有内容后触发
        Sys.WebForms.PageRequestManager.getInstance().add_pageLoaded(TrackPlayBack);
        
        //轨迹回放函数
        function TrackPlayBack()
        {
            var myInput1 = document.getElementById("input1");//用来存放X坐标的控件
            var myInput2 = document.getElementById("input2");
            if(myInput1 != null && myInput2 != null)
            {
                var pointX = myInput1.value.toString();//地图上X坐标点
                var pointY = myInput2.value.toString();//地图上Y坐标点
                if(pointX != "" && pointY != "")
                {
                    var mapImage = document.getElementById("MapControl1_Image");//获取地图控件
                    if(mapImage != null)
                    {
                        //传递URL数据
                        var url = "MapController.ashx?Command=TrackPlayBack&PointX=" + pointX +"&PointY=" + pointY
                        + "&MapAlias=" + mapImage.mapAlias + "&Width=" + mapImage.width +"&Height=" + mapImage.height 
                        + "&ExportFormat=" + mapImage.exportFormat + "&Ran=" + Math.random();
                       
                        //使用Ajax局部刷新更新地图          
                        var xmlHttp = CreateXMLHttp();
                        xmlHttp.open("GET",url,false);   
                        xmlHttp.send();   
                        mapImage.src = url; 
                    }
                }
            }
         }
        </script>
        
        <cc1:MapControl ID="MapControl1" runat="server" Width="800" Height="600" ExportFormat="Jpeg" MapAlias="Map1"/>
        
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <input id="input1" runat="server" type="text" style="width:200;" />
                <input id="input2" runat="server" type="text" style="width:200;" />
                
                <input id="input3" runat="server" type="text" style="width:200;" />
            </ContentTemplate>
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="Timer1" />
            </Triggers>
        </asp:UpdatePanel>

<asp:Timer ID="Timer1" runat="server" Enabled="true" Interval="50" 
            ontick="Timer1_Tick" />

客户端中调用的自定义服务器MapBaseCommand类
/// <summary>
    /// 轨迹回放
    /// </summary>
    [Serializable]
    public class TrackPlayBack : MapBaseCommand
    {
        private Catalog myCatalog = MapInfo.Engine.Session.Current.Catalog;
        /// <summary>
        /// 动画回放图层别名
        /// </summary>
        private string animationName = "动画回放";
        /// <summary>
        /// 动画回放图元Style
        /// </summary>
        private MapInfo.Styles.BitmapPointStyle trackBmpPointStyle = new MapInfo.Styles.BitmapPointStyle("TRUC1-32.BMP", MapInfo.Styles.BitmapStyles.NativeSize, System.Drawing.Color.Blue, 24);

        public TrackPlayBack(string _animationName, MapInfo.Styles.BitmapPointStyle  _trackBmpPointStyle)
        {
            Name = "TrackPlayBack";

            animationName = _animationName;
            trackBmpPointStyle = _trackBmpPointStyle;
        }

        public override void Process()
        {
            //获取分站坐标
            double pointX, pointY;
            double.TryParse(HttpContext.Current.Request["PointX"].ToString(), out pointX);
            double.TryParse(HttpContext.Current.Request["PointY"].ToString(), out pointY);
            //获取实现与执行各种操作的MapContorlModel实例
            MapControlModel myCtrlModel = MapControlModel.GetModelFromSession();
            try
            {
                //获取地图实例
                Map myMap = myCtrlModel.GetMapObj(MapAlias);
                if(myMap != null)
                {
                    //清空地图轨迹回放图元
                    MapInfo.Data.Table myTable = myCatalog.GetTable(animationName);
                    if(myTable != null)
                    {
                        #region 清空图元
                        SearchInfo mySearchInfo = MapInfo.Data.SearchInfoFactory.SearchWhere("");
                        IResultSetFeatureCollection myIRetFeaColl = myCatalog.Search(myTable, mySearchInfo);
                        if(myIRetFeaColl != null)
                        {
                            foreach(Feature myObj in myIRetFeaColl)
                            {
                                myTable.DeleteFeature(myObj);
                            }
                        }
                        #endregion

                        #region 添加图元
                        MapInfo.Geometry.Point myPoint = new MapInfo.Geometry.Point(myMap.GetDisplayCoordSys(), new MapInfo.Geometry.DPoint(pointX, pointY));

                        Feature myFeature = new Feature(myTable.TableInfo.Columns);
                        myFeature.Geometry = myPoint;
                        myFeature.Style = trackBmpPointStyle;

                        myTable.InsertFeature(myFeature);
                        #endregion
                    }
                }
            }
            finally
            {
                System.IO.MemoryStream ms = myCtrlModel.GetMap(MapAlias, MapWidth, MapHeight, ExportFormat);
                StreamImageToClient(ms);
            }

        }
    }

后台代码

//此处使用Timer模拟生成的点作为动态轨迹的坐标点
protected void Timer1_Tick(object sender, EventArgs e)
    {
        double pointX = 4999 + myRandom.NextDouble() * 2;
        double pointY = pointX;

        this.input1.Value = pointX.ToString();
        this.input2.Value = pointY.ToString();
    }

问题：该功能采用异步更新图元位置，并设置Timer的Interval为50ms（甚至更小），使用IE浏览器坐标点更新速度1-3次/s,使用搜狗浏览器坐标点的更新速度则更慢。怎么样才能使更新速度更快，问题出在何处？是MapXtreme异步更新本身的问题吗？