too slow in show report in vb.net 2010 using crytal report - vb.net

Question

I am using this code to show the report
Dim rpt As New CrystalReport1()
Dim sql As String
Dim where As String
If con Is Nothing OrElse con.State = ConnectionState.Closed Then
'MsgBox("closed")
OpenCon()
End If
Dim m As String
m = ""
For Each n As TreeNode In GetCheck(TreeView1.Nodes)
If n.Tag = 1 Then
m = m
Else
If m = "" Then
m = (n.Tag)
Else
m = m & ", " & (n.Tag)
End If
End If
Next
sql = "SELECT [bran_id],[f01],[f02],[f03],[f04],[f05],[f06],[f07],[f08],[bran_name],[comp_id],[comp_name],'" & dtStart.Value.Date & "' AS start_date, '" & dtEnd.Value.Date & "' AS end_date FROM [v_complain]"
If m = "" Then
MsgBox("لم يتم تحديد اى مدينة من فضلك قم بالاختيار اولا")
Exit Sub
Else
where = " WHERE bran_id in (" & m & ") and f02 between CONVERT(date,'" & dtStart.Value.Date & "',103) and CONVERT(date,'" & dtEnd.Value.Date & "',103)"
sql = sql + where
If cbF06.Checked = True Then
where = " AND (f06 like N'') or (f06 is null)"
sql = sql + where
End If
If cbF07.Checked = True Then
where = " AND (f07 like N'') or (f07 is null)"
sql = sql + where
End If
Dim dscmd As New SqlDataAdapter(sql, con)
Dim ds As New DataTable
dscmd.Fill(ds)
rpt.SetDataSource(ds)
CrystalReportViewer1.ReportSource = rpt
CrystalReportViewer1.Refresh()
End If
con.Close()
but it's too slow to show the report in the first time. When I try to run it again without closing the window it work perfectly. Is there any way to make it faster?
Thanks

Answer 1

How slow it is? Several seconds?
I believe it happens do to a need to initialize underling reports 'engine'. I had similar issues and the best I could come up with was to display "Creating report, please wait..." message to a user so they. As an alternative, when you start your app, you can make a 'fake' call to create a dummy report in the background without displaying anything to a user so all required resources will be initialized by the time user is ready to create a real report.