Speed up this loop...

Any suggestion or modification to my code to speed up this loop?


    Private Sub cmbLeaveType_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmbLeaveType.SelectedIndexChanged
 
        RetrieveLeave()
       
    End Sub
 
    Private Sub RetrieveLeave()
        If cmbLeaveType.SelectedItem Is Nothing Then
            Exit Sub
        End If
        Dim ltID As Integer = CType(cmbLeaveType.SelectedItem, ComboItem).Tag
        For i As Integer = 0 To listEmployees.Items.Count - 1
            Application.DoEvents()
            System.Threading.Thread.Sleep(20)
            Dim item As ListViewItem = listEmployees.Items(i)
            Dim leaveCount As Double = Employee.GetNumberOfLeaves(item.Tag, ltID, DBUtils.GetServerDateTime(m_Connection).Year, m_Connection)
            Dim leaveUsed As Double = TimeAttendance.CountAllLeaves(item.Tag, ltID, DBUtils.GetServerDateTime(m_Connection).Year, m_Connection)
            Dim leaveReq As Double = TADBObject.Leave.GetRequestedLeaveCount(item.Tag, ltID, DBUtils.GetServerDateTime(m_Connection).Year, m_Connection)
            '--if edit mode then remove queried requests count
            If m_Leave.LeaveTypeID = ltID Then
                If m_Leave.LeaveApplication = ENUMLEAVEAPPLICATION.Wholeday Then
                    leaveReq -= m_Leave.EndDate.Subtract(m_Leave.StartDate).TotalDays + 1
                Else
                    leaveReq -= 0.5
                End If
            End If
            '--
            Dim leaveRemain As Double = leaveCount - leaveUsed
            If leaveRemain < 0 Then
                leaveRemain = 0
            End If
            Dim leavePending As Double = leaveReq - leaveUsed
            If leavePending < 0 Then
                leavePending = 0
            End If
            item.SubItems(1).Text = leaveRemain.ToString("###,###.##")
            item.SubItems(2).Text = leavePending.ToString("###,###.##")
        Next
    End Sub

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You can still futher optimize by defining a variable to:
DBUtils.GetServerDateTime(m_Connection).Year
so that you only calculate it once.
If this solution is not enough please provide execution time your previous code and this code.
You can try this profiler: (14 day trial)
http://www.red-gate.com/products/ants_performance_profiler/index.htm?gclid=CJ_H9um2pZ0CFRUwpAodyykj3A

Private Sub RetrieveLeave()
        If cmbLeaveType.SelectedItem Is Nothing Then
            Exit Sub
        End If
        listEmployees.BeginUpdate()
        Try
            Dim ltID As Integer = CType(cmbLeaveType.SelectedItem, ComboItem).Tag
            For i As Integer = 0 To listEmployees.Items.Count - 1
                'Application.DoEvents()
                'System.Threading.Thread.Sleep(20)
                Dim item As ListViewItem = listEmployees.Items(i)
                Dim id As String = item.Tag
                Dim leaveCount As Double = Employee.GetNumberOfLeaves(id, ltID, DBUtils.GetServerDateTime(m_Connection).Year, m_Connection)
                Dim leaveUsed As Double = TimeAttendance.CountAllLeaves(id, ltID, DBUtils.GetServerDateTime(m_Connection).Year, m_Connection)
                Dim leaveReq As Double = TADBObject.Leave.GetRequestedLeaveCount(id, ltID, DBUtils.GetServerDateTime(m_Connection).Year, m_Connection)
                '--if edit mode then remove queried requests count
                If m_Leave.LeaveTypeID = ltID Then
                    If m_Leave.LeaveApplication = ENUMLEAVEAPPLICATION.Wholeday Then
                        leaveReq -= m_Leave.EndDate.Subtract(m_Leave.StartDate).TotalDays + 1
                    Else
                        leaveReq -= 0.5
                    End If
                End If
                '--
                Dim leaveRemain As Double = leaveCount - leaveUsed
                If leaveRemain < 0 Then
                    leaveRemain = 0
                End If
                Dim leavePending As Double = leaveReq - leaveUsed
                If leavePending < 0 Then
                    leavePending = 0
                End If
                item.SubItems(1).Text = leaveRemain.ToString("###,###.##")
                item.SubItems(2).Text = leavePending.ToString("###,###.##")
            Next
 
        Finally
            listEmployees.BeginUpdate()
            Application.DoEvents()
        End Try
 
    End Sub

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'Simplified psuedo-code Dim Conn Conn.Open For i=0 to listEmployees.Items.Count - 1 something = MySub(Conn, param1, param2) Next private sub MySub(ByVal Conn As Connection, ByVal Param1 as Object, ByVal Parm2 as Object) 'Use Conn here for all DB calls. End Sub

Question

Speed up this loop...

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Microsoft Visual Basic.Net

.NET

Visual Studio

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