基准化.Net正则表达式选项-或RightToLeft做什么？

我创建了一个演示应用程序来测试某些正则表达式的性能。我的第三个测试使用选项RightToLeft。

看来它大大加快了流程！为什么？它有什么作用？

这是我的测试应用程序：

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        private const string IsRequestForDirectoryWithoutTrailingSlashRegex = @"^(?#Path:)(.*/)?(?#LastPart:)(?<!\.asmx|\.aspx/)([^./?#]+?)(?#QueryString:)(\?.*?)(?#Anchor:)?(#.*)?$";

        private static string[] Tests = new string[] {
            "http://localhost/manager/page.aspx",
            "http://localhost/manager/",
            "http://localhost/manager",
            "http://localhost/manager/?param=value",
            "http://localhost/manager/dir?param=value"
        };

        static void Main(string[] args)
        {
            Test1();
            Test2();
            Test3();
            Test4();

            Console.WriteLine();
            Console.ReadLine();
        }

        public static void Test1()
        {
            Regex regex = new Regex(IsRequestForDirectoryWithoutTrailingSlashRegex);
            DoWork("1", regex);
        }

        public static void Test2()
        {
            Regex regex = new Regex(IsRequestForDirectoryWithoutTrailingSlashRegex, RegexOptions.Compiled);
            DoWork("2", regex);
        }

        public static void Test3()
        {
            Regex regex = new Regex(IsRequestForDirectoryWithoutTrailingSlashRegex, RegexOptions.Compiled | RegexOptions.RightToLeft);
            DoWork("3", regex);
        }

        public static void Test4()
        {
            Regex regex = new Regex(IsRequestForDirectoryWithoutTrailingSlashRegex, RegexOptions.Compiled | RegexOptions.RightToLeft | RegexOptions.IgnoreCase);
            DoWork("4", regex);
        }
        static void DoWork(string name, Regex regex)
        {
            Stopwatch sp = new Stopwatch();
            sp.Start();

            for (int i = 0; i < 100000; i++)
            {
                foreach (string s in Tests)
                {
                    regex.IsMatch(s);
                }
            }

            foreach (string s in Tests)
            {
                Console.WriteLine(":" + s + ":" + regex.IsMatch(s).ToString());
            }

            sp.Stop();

            Console.WriteLine("Test " + name + ": " + sp.ElapsedTicks);
        }
    }
}