• http://blog.nhcomputerlearning.com/2012/06/06/speed-up-your-scrolling-in-large-word-documents/
• http://www.howtogeek.com/74007/how-to-speed-up-microsoft-word-2007-and-2010/

• https://word.tips.net/T001337_Removing_Unused_Styles.html

Sub DeleteUnusedStyles()
    Dim oStyle As Style
 
    For Each oStyle In ActiveDocument.Styles
        'Only check out non-built-in styles
        If oStyle.BuiltIn = False Then
            With ActiveDocument.Content.Find
                .ClearFormatting
                .Style = oStyle.NameLocal
                .Execute FindText:="", Format:=True
                If .Found = False Then oStyle.Delete
            End With
        End If
    Next oStyle
End Sub