Sebastian,
I can't provide a live URL. I've since discovered that the performance is related to whether the calander control is within a container within the Update panel e.g. The following code performs very poorly within IE6:
<asp:UpdatePanel ID="updTelerik" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:Panel ID="Panel2" runat="server" Style="display: none; margin: 0px;">
<telerik:RadTabStrip ID="RadTabStrip1" runat="server" Skin="Vista" MultiPageID="RadMultiPage1"
SelectedIndex="0" Align="Justify" ReorderTabsOnSelect="true" Width="347px" >
<Tabs>
<telerik:RadTab Text="Calander View">
</telerik:RadTab>
<telerik:RadTab Text="Recurrence">
</telerik:RadTab>
</Tabs>
</telerik:RadTabStrip>
<telerik:RadMultiPage ID="RadMultiPage1" runat="server" SelectedIndex="0" CssClass="pageView" Width="345px">
<telerik:RadPageView ID="RadPageView1" runat="server" >
<telerik:RadCalendar ID="RadCalendar1" runat="server" Font-Names="Arial, Verdana, Tahoma"
ForeColor="Black" Style="border-color: #ececec" MultiViewColumns="3" EnableViewSelector="True"
MultiViewRows="1" OnDefaultViewChanged="RadCalendar1_OnDefaultViewChanged" AutoPostBack="true"
Visible="true" OnSelectionChanged="RadCalendar1_OnSelectionChanged" EnableNavigationAnimation="false">
</telerik:RadCalendar>
</telerik:RadPageView>
<telerik:RadPageView ID="RadPageView2" runat="server">
<div id="divMainRecurrence" runat="server" visible="true">
</div>
</telerik:RadPageView>
</telerik:RadMultiPage>
</asp:Panel>
<asp:HyperLink ID="lnkHiddenPopup" runat="server" Style="display: none;">Hidden Popup</asp:HyperLink>
<ajaxToolkit:ModalPopupExtender ID="mpeCalendar" runat="server" PopupControlID="Panel2"
TargetControlID="lnkHiddenPopup">
</ajaxToolkit:ModalPopupExtender>
<asp:Button ID="btnTest" runat="server" Text="Test2" OnClick="btnTest_Click" />
</ContentTemplate>
</asp:UpdatePanel>
If I take the calander control out of the tab strip then the performance improves e.g :
<asp:UpdatePanel ID="updTelerik" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:Panel ID="Panel2" runat="server" Style="display: none; margin: 0px;">
<telerik:RadCalendar ID="RadCalendar1" runat="server" Font-Names="Arial, Verdana, Tahoma"
ForeColor="Black" Style="border-color: #ececec" MultiViewColumns="3" EnableViewSelector="True"
MultiViewRows="1" OnDefaultViewChanged="RadCalendar1_OnDefaultViewChanged" AutoPostBack="true"
Visible="true" OnSelectionChanged="RadCalendar1_OnSelectionChanged" EnableNavigationAnimation="false">
</telerik:RadCalendar>
</asp:Panel>
<asp:HyperLink ID="lnkHiddenPopup" runat="server" Style="display: none;">Hidden Popup</asp:HyperLink>
<ajaxToolkit:ModalPopupExtender ID="mpeCalendar" runat="server" PopupControlID="Panel2"
TargetControlID="lnkHiddenPopup">
</ajaxToolkit:ModalPopupExtender>
<asp:Button ID="btnTest" runat="server" Text="Test2" OnClick="btnTest_Click" />
</ContentTemplate>
</asp:UpdatePanel>
The performance issue is not related specifically to the tap strip control. It is related to the calendar when it is inside any container control that is also inside an update panel.
These performance issues appear specific to IE6. I haven't tried it on IE7 yet. The performance is fine on Firefox.
Regards
Myles