我设计了一个程序，在 RichTextBox 的 TextChanged 事件，通过 For...Next... 枚举每个字符，将其中的尖括号（ <> ）、双引号（ "" ）中的文字换成不同的颜色。
这是我的代码：

 Public Class FrmEdit
    Private Sub CodeTextBox_TextChanged(sender As Object, e As EventArgs) Handles CodeTextBox.TextChanged
        If CodeTextBox.Text = "" Then Exit Sub
        CodeTextBox.ForeColor = Color.Black
        CodeTextBox.SelectAll() : CodeTextBox.SelectionFont = Me.Font
        TipProgressBar.Visible = True
        TipProgressBar.Maximum = CodeTextBox.TextLength - 1
        TipProgressBar.Minimum = 0
        TipProgressBar.Value = 0

        Dim AngleBracketsOn As Boolean = False
        Dim DoubleQuotesOn As Boolean = False

        For i As Integer = 0 To CodeTextBox.TextLength - 1
            CodeTextBox.SelectionStart = i
            CodeTextBox.SelectionLength = 1

            If CodeTextBox.SelectedText = "<" Then
                AngleBracketsOn = True
                CodeTextBox.SelectionLength = CodeTextBox.TextLength - i
                CodeTextBox.SelectionColor = Color.Purple
            End If
            If CodeTextBox.SelectedText = ">" Then
                If AngleBracketsOn = True Then
                    AngleBracketsOn = False
                    CodeTextBox.SelectionStart = i + 1
                    CodeTextBox.SelectionLength = CodeTextBox.TextLength - i - 1
                    CodeTextBox.SelectionColor = Color.Black
                End If
            End If

            If CodeTextBox.SelectedText = """" Then
                If DoubleQuotesOn = False Then
                    DoubleQuotesOn = True
                    CodeTextBox.SelectionLength = CodeTextBox.TextLength - i
                    CodeTextBox.SelectionColor = Color.Blue
                Else
                    DoubleQuotesOn = False
                    CodeTextBox.SelectionStart = i + 1
                    CodeTextBox.SelectionLength = CodeTextBox.TextLength - i - 1
                    CodeTextBox.SelectionColor = Color.Black
                End If
            End If

            TipProgressBar.Value = i
        Next

        CodeTextBox.SelectionLength = 0
        CodeTextBox.SelectionStart = CodeTextBox.TextLength
        TipProgressBar.Visible = False
    End Sub
End Class

我复制了一段百度翻译网页（ http://fanyi.baidu.com/#en/zh/ ）的源代码，卡了9分钟才完成。不知道有没有更好的办法，可以加快程序的速度？求大神帮忙！