Hi,

I have 2 multiselect listboxes in my webpage. when the selected index of first listbox is changed, it updates the second listbox. there are only 10 items in first listbox and 45 items in second listbox when all the 10 items in first listbox are selected. Autopostback for first listbox is set to true and selectedindexchanged event has code to update the second listbox from database. For some reason, this process is very-2 slow, even if I select only one item in first, it takes around 15-16 seconds to load second listbox. I have a RadGrid in the page which is loaded when a button is clicked. I have separate RadAjaxManager setting for button update and listbox update. Can you please suggest how can I make the listbox load faster or what should I check to solve this problem? I also noticed that most of the pages are faster without AJAX. I have gone through the document on Telerik about how to make AJAX faster and have implemenetd the ASP Scriptmanager setting to be in release mode and also debug=false web config setting.

Thanks.

Hi Kachy,

I'm not sure if I completely understand the exact scenario and the issue you are facing. Does the application runs faster if the Ajax is disabled on the page? Also what are the results if you are using regular asp UpdatePanel instead of RadAjax? 
Please confirm if there are any tables that are rendered more than one time on the page. For more information on the RadAjax performance optimization please review the following help topic.

Best wishes,
Maria Ilieva
the Telerik team

I used Fiddler to check my packet size and this is the detail

On Page load
Bytes Sent:  3,213
Bytes Received: 253,154

List Box Selected Index Changed
Bytes Sent:  67,791
Bytes Received: 59,428

second time listbox selected index change
Bytes Sent:  68,155
Bytes Received: 59,718

Clicked on Search Button, so the grid loaded
Bytes Sent:  68,421
Bytes Received: 448,327

After grid is loaded, listbox selected index changed
Bytes Sent:  242,888
Bytes Received: 233,327

In my page, there are 2 ASP Listboxes. When the value of first one changes, second Listbox is repopulated. There are other parameters for search like name, dob etc.
There is a search button, when search button is clicked, all the parameters needed for search is sent to the server and grid gets populated. If you see the Bytes Sent and Bytes Received above, if I select the Listbox1 after the grid is laoded, the bytes sent and received is far more than when the grid is not loaded. As per my understanding of Ajax, when I select the first Listbox irrespective of whatever else is on page, it should send the Listbox1 value to the server and bring me back the listbox2 value. why the bytes sent and bytes received in second scenario, when the grid is populated is so high as compared to when the grid is not loaded.

This is my RadAjaxManagerSetting:

<telerik:RadAjaxManager ID="RadAjaxManager1" runat="server" EnableAJAX="true"
        onajaxrequest="RadAjaxManager1_AjaxRequest">
        <ClientEvents OnRequestStart="OnRequestStart" />
    <AjaxSettings>
        <telerik:AjaxSetting AjaxControlID="RadAjaxManager1">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="RadGrid" />
                <telerik:AjaxUpdatedControl ControlID="ListBoxAll1" />
                <telerik:AjaxUpdatedControl ControlID="ListBoxAll2" />
            </UpdatedControls>
        </telerik:AjaxSetting>
        <telerik:AjaxSetting AjaxControlID="RadGrid">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="RadGrid" />
            </UpdatedControls>
        </telerik:AjaxSetting>
        <telerik:AjaxSetting AjaxControlID="ListBox1">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="ListBox2" />
            </UpdatedControls>
        </telerik:AjaxSetting>
        <telerik:AjaxSetting AjaxControlID="buttonSearch">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="RadGrid" />
                <telerik:AjaxUpdatedControl ControlID="buttonSearch" />
                <telerik:AjaxUpdatedControl ControlID="labelMessage" />
            </UpdatedControls>
        </telerik:AjaxSetting>
        <telerik:AjaxSetting AjaxControlID="RadMenu1">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="RadGrid"/>
            </UpdatedControls>
        </telerik:AjaxSetting>
   </AjaxSettings>
</telerik:RadAjaxManager>

RadMenu1 is the ContextMent for RadGrid.  labelMessage is a Label control to show if error occurs during search. I have added ListBox1 and ListBox2 as Updated Control for RadAjaxManager1 because in IE6, if I don't add that, ListBox1, ListBox2 disappears after grid is refreshed when any context menu is clicked.
Can you please let me know whether the RadAjaxManager settings are ok or not and why this problem occurs.

Thanks.

Hello Kachy,

Based on the supplied information, it is hard to determine what is causing the performance issue. However, to properly address the problem, it will be best if you open a formal support ticket, and send us a small working project, demonstrating your setup, and showing the unwanted behavior. We will debug it locally, and get back to you with more information on the matter.

All the best,
Pavlina
the Telerik team