byte[] vs IList<byte> performance comparison

Array-vs-IList.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;

namespace ConsoleApp1
{
        class Program {
        static volatile byte res1, res2;
    
        static void Main(string[] args) {
            var sw = new Stopwatch();
            var rnd = new Random();
    
            var bytes = new byte[1024 * 1024 * 1024];
            rnd.NextBytes(bytes);
    
            GC.Collect();
            GC.WaitForPendingFinalizers();
            GC.Collect();
            sw.Start();
            res1 = TestArray(bytes);
            sw.Stop();
    
            var time1 = sw.ElapsedMilliseconds;
    
            GC.Collect();
            GC.WaitForPendingFinalizers();
            GC.Collect();
            sw.Restart();
            res2 = TestIList(bytes);
            sw.Stop();
    
            var time2 = sw.ElapsedMilliseconds;
    
            Console.WriteLine($"byte[] took:      {time1} ms");
            Console.WriteLine($"IList<byte> took: {time2} ms");
        }
    
        static byte TestArray(byte[] val) {
            var res = val[0];
    
            for (var i = 0; i < val.Length; i++)
                res ^= val[i];
    
            return res;
        }
    
        static byte TestIList(IList<byte> val) {
            var res = val[0];
    
            var len = val.Count;
            for (var i = 0; i < len; i++)
                res ^= val[i];
    
            return res;
        }
    }
}