Replace multiple strings in single pass (based on regular expressions)

StringMultiReplace.cs

using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace MultiReplace
{
    public sealed class StringMultiReplace
    {
        #region Private Members

        private readonly Regex regex;
        private readonly Dictionary<string, string> map;

        #endregion

        #region Constructors

        public StringMultiReplace(Dictionary<string, string> map, RegexOptions regexOptions) :
            this(map.Keys, regexOptions)
        {
            this.map = map;
        }

        public StringMultiReplace(IEnumerable<string> searchPatterns, RegexOptions regexOptions)
        {
            regex = new Regex("(" + String.Join("|", searchPatterns) + ")", regexOptions);
        }

        #endregion

        #region Public Methods

        public string Replace(string input)
        {
            return regex.Replace(input, m => map[m.Groups[0].Value]);
        }

        public string Replace(string input, string replacement)
        {
            return regex.Replace(input, replacement);
        }

        public string Replace(string input, MatchEvaluator evaluator)
        {
            return regex.Replace(input, evaluator);
        }

        #endregion

        #region Static Methods
        
        public static string SlowReplace(string input, Dictionary<string, string> map, RegexOptions regexOptions)
        {
            return new StringMultiReplace(map, regexOptions).Replace(input, m => map[m.Groups[0].Value]);
        }

        #endregion
    }
}