newstring vs regex, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Diagnostics;
namespace Rextester
{
    public class Program
    {
        
        public static void Main(string[] args)
        {
            //Your code goes here
            var x = "+1 (403) 555-1234";
            Console.WriteLine(x);
            
            var y = GetNumbers(x);
            var z = GetNumbersRegex(x);
                
            Console.WriteLine(y);
            Console.WriteLine(z);
        }
        
        private static string GetNumbers(string input)
        {
            var timer = new Stopwatch();
            timer.Start();
            var result = new string(input.Where(c => char.IsDigit(c)).ToArray());
            timer.Stop();
            Console.WriteLine("Strip milliseconds: {0}", timer.ElapsedMilliseconds);
            return result;
        }
        
        private static string GetNumbersRegex(string input){
            
            var timer = new Stopwatch();
            timer.Start();
            var result = Regex.Replace(input, "[^0-9]", "");
            
            timer.Stop();
            Console.WriteLine("Regex milliseconds: {0}", timer.ElapsedMilliseconds);
            return result;
        }
      
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,16 sec, absolute running time: 0,17 sec, cpu time: 0,16 sec, average memory usage: 17 Mb, average nr of threads: 4