Examples of Optimization in VB/VBA/VB.net?

Dim data As AnyDataType  ' right (strongly typed)'
Dim data As Object       ' wrong (weakly typed)'
Dim data                 ' wrong (weakly typed; defaults to the Object)'

Dim config As ConfigStruct  ' right (when config holds small amount of data)'
Dim config As ConfigClass   ' wrong (when config holds small amount of data)'

Range("B1").Formula = "Hello there!"

Range("B1").Formula = "Hello there!"

Private Sub DoStuff()
    Dim objMyFoo As New FooClass

    ' use objMyFoo

    ' done with objMyFoo
    Set objMyFoo = Nothing

    ' do some more stuff
End Sub

For each ctl as Control in Form1.Controls
  Dim string1 as String = ctl.ID
  Dim string2 as String = ctl.ToolTip
  Dim string3 as String = ctl.Text
  Dim string4 as String = ctl.BackColor.ToString()
  'do things with the strings
Next

Dim string1 as String
Dim string2 as String
Dim string3 as String
Dim string4 as String

For each ctl as Control in Form1.Controls
  string1 = ctl.ID
  string2 = ctl.ToolTip
  string3 = ctl.Text
  string4 = ctl.BackColor.ToString()
  'do things with the strings
Next

For _x as Integer = 0 To 5

  Dim _y as Integer

  If _x % 2 = 0 Then
    _y = _x
  End If

  Console.WriteLine(_y)
Next

Dim _y as Integer

For _x as Integer = 0 To 5

  _y = 0

  If _x % 2 = 0 Then
    _y = _x
  End If

  Console.WriteLine(_y)
Next

' For Buy & Sell Sheets, Fill all ComboBoxes and Clear contents
    For Each initsheet In Worksheets
        If (Left$(initsheet.Name, 3) = "Buy" Or Left$(initsheet.Name, 4) = "Sell") Then
            initsheet.Activate
            For Each cCont In ActiveSheet.OLEObjects
            ' Cycle through all controls, filling all ComboBoxes
                If TypeOf cCont.Object Is MSForms.ComboBox Then
                    With cCont
                        Select Case Left$(.Name, 5)
                            Case "cmbMW"
                                .ListFillRange = parSheet.Name & "!" & parSheet.Range("transUnit", Sheet2.Range("transUnit").End(xlDown)).Address
                                .Object.ListIndex = 0
                            Case "cmbTy"
                                .ListFillRange = parSheet.Name & "!" & parSheet.Range("transType", Sheet2.Range("transType").End(xlDown)).Address
                                .Object.ListIndex = 0
                            Case "cmbCo"
                                .ListFillRange = parSheet.Name & "!" & parSheet.Range("transCo", Sheet2.Range("transCo").End(xlDown)).Address
                                .Object.ListIndex = 0
                            Case "cmbSe"
                                .Object.List() = ServerArray
                        End Select
                    End With
                End If
            Next cCont
            Range("B6:K30").ClearContents
        End If
    Next initsheet