string concat vs string interpolate.cs

using System.Collections.Generic;
using System.Text;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

namespace TestHub
{
    class Program
    {
        public static void Main(string[] args)
        {
            var summary = BenchmarkRunner.Run(typeof(Program).Assembly);
        }
    }

    public class StringTest
    {
        private object[] Items;
        private string formatTemplate = string.Empty;
        public StringTest()
        {
            var count = 0;
            var builder = new StringBuilder();
             var arrs= new List<object>();
            do
            {
                builder.Append($"{count}");
                arrs.Add(new object());
                count++;                
            } while (count < 5000);
            formatTemplate = builder.ToString();
            Items = arrs.ToArray();
        }

        [Benchmark]
        public string Concat()
        {
            return string.Concat(Items);
        }
        [Benchmark]
        public string Format()
        {
            return string.Format(formatTemplate, Items);
        }
    }
}