How to Toggle String Case in .NET

The following snippet shows how to toggle string casing in .NET:

public string ToggleCase(string input)
{
    string result = string.Empty;
    char[] inputArray = input.ToCharArray();

    foreach (char c in inputArray)
    {
        if (char.IsLower(c))
            result += c.ToString().ToUpper();
        else if (char.IsUpper(c))
            result += c.ToString().ToLower();
        else
            result += c.ToString();
    }

    return result;
}

This code snippet could be simplified as follows:

public string ToggleCase(string input)
{
    string result = string.Empty;
    char[] inputArray = input.ToCharArray();
    foreach (char c in inputArray)
    {
        if (char.IsLower(c))
            result += Char.ToUpper(c);
        else
            result += Char.ToLower(c);
    }
    return result;
}

But still performance of Alternate 1 and Alternate 2 is 2...3 times better than of this one: see the online comparative test at: http://webinfocentral.com/resources/toggleCaseAlgorithm.aspx[^]

Regards,
Alex Bell