gistfile1.txt

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;
using System.Buffers;
using System.Security.Cryptography;
using System.Text;
BenchmarkRunner.Run<HashBench>();


[MemoryDiagnoser]
public class HashBench
{
    [Params(10, 100, 800)]
    public int Size
    {
        get => Key.Length;
        set
        {
            if (Size != value)
            {
                var rand = new Random(12345);
                char[] chars = ArrayPool<char>.Shared.Rent(value);
                for(int i = 0; i < value; i++)
                {
                    chars[i] = (char)rand.Next(32, 128);
                }
                Key = new string(chars, 0, value);
                ArrayPool<char>.Shared.Return(chars);
            }
        }
    }

    public static readonly StringComparer Comparer = StringComparer.Ordinal;

    public string Key { get; set; } = "";

    [Benchmark(Baseline = true)]
    public void DirectOrdinal()
    {
        var key = Key;
        _ = Comparer.GetHashCode(key);
        _ = Comparer.Equals(key, key);
    }


    [Benchmark]
    public void DirectNatural()
    {
        var key = Key;
        _ = key.GetHashCode();
        _ = key.Equals(key);
    }

    [Benchmark]
    public void ViaHashedKey()
    {
        var hashed = GetHashedCacheKey(Key);
        _ = hashed.GetHashCode();
        _ = hashed.Equals(hashed);
    }

    private static string GetHashedCacheKey(string key)
    {
        using var md5 = MD5.Create();
        var inputAsBytes = Encoding.UTF8.GetBytes(key);
        var hashBytes = md5.ComputeHash(inputAsBytes);

        var sb = new StringBuilder();
        foreach (var byt in hashBytes)
        {
            sb.Append(byt.ToString("X2"));
        }

        return sb.ToString();
    }
}

results.md

Method	Size	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
DirectOrdinal	10	4.339 ns	0.0131 ns	0.0116 ns	1.00	0.00	-	-	NA
DirectNatural	10	4.454 ns	0.0141 ns	0.0132 ns	1.03	0.00	-	-	NA
ViaHashedKey	10	495.167 ns	9.1316 ns	8.5417 ns	114.13	1.93	0.0629	1056 B	NA
DirectOrdinal	100	45.495 ns	0.4241 ns	0.3967 ns	1.00	0.01	-	-	NA
DirectNatural	100	44.201 ns	0.1409 ns	0.1177 ns	0.97	0.01	-	-	NA
ViaHashedKey	100	573.756 ns	6.8082 ns	6.3684 ns	12.61	0.17	0.0677	1144 B	NA
DirectOrdinal	800	363.484 ns	2.3475 ns	2.0810 ns	1.00	0.01	-	-	NA
DirectNatural	800	361.123 ns	0.9744 ns	0.9114 ns	0.99	0.01	-	-	NA
ViaHashedKey	800	1,479.989 ns	4.5036 ns	4.2126 ns	4.07	0.03	0.1087	1840 B	NA