String.Create v String.Join for simple string concat

stringJoinVstringCreateSimpleConcat.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Columns;
using BenchmarkDotNet.Configs;
using BenchmarkDotNet.Environments;
using BenchmarkDotNet.Jobs;
using BenchmarkDotNet.Reports;
using System;
using System.Text;

namespace BenchmarkDotNet.Samples
{
    [MemoryDiagnoser]
    [Config(typeof(Config))]
    [SimpleJob(RuntimeMoniker.Net80)]
    [HideColumns(Column.Job, Column.RatioSD, Column.AllocRatio)]
    public class StringJoinVStringCreateSimpleConcat
    {
        private class Config : ManualConfig
        {
            public Config()
            {
                SummaryStyle =
                    SummaryStyle.Default.WithRatioStyle(RatioStyle.Percentage);
            }
        }

        private string
            title = "Mr.", firstName = "David", middleName = "Patrick", lastName = "Callan";

        [Benchmark(Baseline = true)]
        public string StringCreate()
        {
            return string.Create(title.Length + firstName.Length + middleName.Length + lastName.Length + 3,
                (title, firstName, middleName, lastName),
                (span, state) =>
                {
                    state.title.AsSpan().CopyTo(span);
                    span = span.Slice(state.title.Length);
                    span[0] = ' ';
                    span = span.Slice(1);

                    state.firstName.AsSpan().CopyTo(span);
                    span = span.Slice(state.firstName.Length);
                    span[0] = ' ';
                    span = span.Slice(1);

                    state.middleName.AsSpan().CopyTo(span);
                    span = span.Slice(state.middleName.Length);
                    span[0] = ' ';
                    span = span.Slice(1);

                    state.lastName.AsSpan().CopyTo(span);
                }
            );
        }

        [Benchmark]
        public string StringConcat()
        {
            return string.
                Concat(new String[] { title, " ", firstName, " ", middleName, " ", lastName });
        }

    }
}