RadCalendar load so slow

[Duong]

I have used RadCalendar to display specify dates. Appointment is a object with propertes : StartTime and EndTime
In codebehind, i used event DayRender to display dates between StartTime and EndTime each of appointment.
With only some appointment, RadCalendar still load so slow.
Sorry my bad english.
Here my code:
ascx.vb
       

Protected Sub RadCalendar1_DayRender(ByVal sender As Object, ByVal e As DayRenderEventArgs) Handles RadCalendar1.DayRender

      

            Dim Specificdate As DateTime = e.Day.Date

            Dim flag = False

            Dim lst As List(Of AIAppointmentInfo) = ctlAIAppointment.GetByUserId(UserInfo.UserID)

            For Each obj As AIAppointmentInfo In lst

                If flag = False Then

                    If Specificdate >= obj.StartTime And Specificdate <= obj.EndTime Then

                        e.Cell.CssClass = "SpecificDay"

                        flag = True

                    ElseIf Specificdate.Day = obj.StartTime.Day And Specificdate.Month = obj.StartTime.Month And Specificdate.Year = obj.StartTime.Year Then

                        e.Cell.CssClass = "SpecificDay"

                        flag = True

                    End If

                End If

 

            Next

 End Sub


ascx

<telerik:RadCalendar runat="server" ID="RadCalendar1" Skin="Hay" AutoPostBack="False"
                    EnableMultiSelect="false" DayNameFormat="FirstTwoLetters" EnableNavigation="true"
                    EnableMonthYearFastNavigation="false" IsTodayHighlighted="true"
                   >
    <SpecialDays>
    <telerik:RadCalendarDay Repeatable="Today" Date="" ItemStyle-CssClass="rcToday" />
    </SpecialDays>
</telerik:RadCalendar>

[Angel Petrov]

Hello Duong,

You should not experience poor performance in your case. Could you ensure that the delay is due to the CSS classes being applied? In the code you have provided I see two different operations:

1. Extracting data
2. Iterating through the data items

If you have a large number of data this could cause the delay in your case. I have created a simple project in which I change the styles of the calendar and I did not experience any performance problems (you could find the demo in the attachments). Please elaborate more on the way you extract the data and the size of the collection.

Kind regards,
Angel Petrov
the Telerik team