Why is this regular expression faster?

public static string StripStringFormating(string formattedString)
{
    if (rTest.IsMatch(formattedString))
        return rTest.Replace(formattedString, string.Empty);
    else
        return formattedString;
}

static Regex rText = new Regex(@"e[[d;]+m", RegexOptions.Compiled);

static Regex rTest =
              new Regex(@"(e([([d;]*[mz]?))?)?", RegexOptions.Compiled);

"(e[(d{1,2};)*?[mz]?)?"

public static string StripStringFormating(string formattedString)
{
    return rTest.Replace(formattedString, string.Empty);
}

(?s)(?:e[(?:(d+);?)*([A-Za-z])(.*?))(?=e[|z)

<ESC>[1;32mThis is bright green.<ESC>[0m This is the default color.

[ [1, 32], m, This is bright green.]
[0, m, This is the default color.]