Formatar Cpf benchmark

readme.md

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.18363.1500 (1909/November2018Update/19H2)
Intel Core i7-8665U CPU 1.90GHz (Coffee Lake), 1 CPU, 8 logical and 4 physical cores
.NET Core SDK=5.0.202
  [Host]     : .NET Core 5.0.5 (CoreCLR 5.0.521.16609, CoreFX 5.0.521.16609), X64 RyuJIT
  DefaultJob : .NET Core 5.0.5 (CoreCLR 5.0.521.16609, CoreFX 5.0.521.16609), X64 RyuJIT

Method	Mean	Error	StdDev	Ratio	RatioSD	Gen 0	Gen 1	Gen 2	Allocated
FormataComSpan	46.58 ns	0.843 ns	0.748 ns	0.35	0.01	0.0134	-	-	56 B
FormataComSpanSlice	32.54 ns	0.621 ns	1.337 ns	0.25	0.01	0.0134	-	-	56 B
FormataComIndexRange	131.05 ns	2.641 ns	2.470 ns	1.00	0.03	0.0591	-	-	248 B
FormataComSubString	131.81 ns	2.256 ns	2.414 ns	1.00	0.00	0.0629	-	-	264 B

FormatarCpf.cs

using BenchmarkDotNet.Attributes;
using System;

namespace RemoveLater
{
    [MemoryDiagnoser]
    public class FormatarCpf
    {
        private string _cpf;

        [GlobalSetup]
        public void Setup()
        {
            _cpf = "12345678901";
        }

        [Benchmark]
        public string FormataComSpan()
        {
            var cpfSpan = _cpf.AsSpan();
            Span<char> cpfFormatado = stackalloc char[14];
            cpfFormatado[3] = '.';
            cpfFormatado[7] = '.';
            cpfFormatado[11] = '-';
            for (var i = (src: 0, dest: 0); i.src < 11;)
            {
                if (i.src == 3 || i.src == 6 || i.src == 9)
                    i.dest++;
                cpfFormatado[i.dest] = cpfSpan[i.src];
                i = (i.src + 1, i.dest + 1);
            }
            return cpfFormatado.ToString();
        }

        [Benchmark]
        public string FormataComSpanSlice()
        {
            var cpfSpan = _cpf.AsSpan();
            Span<char> cpfFormatado = stackalloc char[14];
            cpfFormatado[3] = '.';
            cpfFormatado[7] = '.';
            cpfFormatado[11] = '-';
            cpfSpan.Slice(0, 3).CopyTo(cpfFormatado.Slice(0, 3));
            cpfSpan.Slice(3, 3).CopyTo(cpfFormatado.Slice(4, 3));
            cpfSpan.Slice(6, 3).CopyTo(cpfFormatado.Slice(8, 3));
            cpfSpan.Slice(9, 2).CopyTo(cpfFormatado.Slice(12, 2));
            return cpfFormatado.ToString();
        }

        [Benchmark]
        public string FormataComIndexRange()
        {
            return $"{_cpf[0..2]}.{_cpf[3..5]}.{_cpf[6..8]}-{_cpf[9..10]}";
        }

        [Benchmark(Baseline = true)]
        public string FormataComSubString()
        {
            return $"{_cpf.Substring(0, 3)}.{_cpf.Substring(3, 3)}.{_cpf.Substring(6, 3)}-{_cpf.Substring(9, 2)}";
        }
    }
}