.NET 8 simple string concatenation benchmarks

stringConcatenationDotnet8.cs

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

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

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

        [Benchmark]
        public string StringBuilder()
        {
            var stringBuilder =
                new StringBuilder();

            return stringBuilder
                .Append(title).Append(' ')
                .Append(firstName).Append(' ')
                .Append(middleName).Append(' ')
                .Append(lastName).ToString();
        }

        [Benchmark]
        public string StringBuilderExact24()
        {
            var stringBuilder =
                new StringBuilder(24);

            return stringBuilder
                .Append(title).Append(' ')
                .Append(firstName).Append(' ')
                .Append(middleName).Append(' ')
                .Append(lastName).ToString();
        }

        [Benchmark]
        public string StringBuilderEstimate100()
        {
            var stringBuilder =
                new StringBuilder(100);

            return stringBuilder
                .Append(title).Append(' ')
                .Append(firstName).Append(' ')
                .Append(middleName).Append(' ')
                .Append(lastName).ToString();
        }

        [Benchmark]
        public string StringPlus()
        {
            return title + ' ' + firstName + ' ' +
                middleName + ' ' + lastName;
        }

        [Benchmark]
        public string StringFormat()
        {
            return string.Format("{0} {1} {2} {3}",
                title, firstName, middleName, lastName);
        }

        [Benchmark]
        public string StringInterpolation()
        {
            return
            $"{title} {firstName} {middleName} {lastName}";
        }

        [Benchmark]
        public string StringJoin()
        {
            return string.Join(" ", title, firstName,
                middleName, lastName);
        }

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

        [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);
                }
            );
        }
    }
}

You can also do string interpolation with the last example using TryWrite:

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

    public string StringCreate()
    {
        return string.Create(title.Length + firstName.Length + middleName.Length + lastName.Length + 3,
            (title, firstName, middleName, lastName),
            (span, state) => span.TryWrite($"{state.title} {state.firstName} {state.middleName} {state.lastName}", out _));
    }
}

Thanks David, I had no idea you could do this, it's a lot cleaner.
Very helpful thank you.

@davepcallan Appreciate the awesome tests-suite here and the benchmarks. Quick question off of the top of my head (might be suggesting something wacky - bear with me):

Would it be possible and would it help at all in terms of performance to get the bytes in the callback of String.Create() as UTF8?

Thanks again!