"ajaxToolkit:CalendarExtender" Taking long time to open calendar

Hi

I am using "ajaxToolkit:CalendarExtender" control. Here is sample code.

Problem is, it takes long time to open calendar. can we do some thing to minimize the time it takes to open calendar??

Thanks in Advance. 

<asp:TextBox ID="txtStartDate" runat="server" MaxLength="30" Columns="20"></asp:TextBox>                  
                        <asp:Image ID="DateStart" runat="server" ImageUrl="~/Images/Calendar_scheduleHS.png" ImageAlign="middle" />
                        <ajaxToolkit:CalendarExtender runat="server"
                            TargetControlID="txtStartDate"                                                  
                            PopupButtonID="DateStart"                           
                             >                          
                            </ajaxToolkit:CalendarExtender>