C# Academy · Lesson

Benchmarking with BenchmarkDotNet

Write accurate micro-benchmarks with BenchmarkDotNet, analyze throughput and allocations, and avoid common pitfalls.

Why BenchmarkDotNet?

Micro-benchmarking is surprisingly hard: JIT warm-up, GC pauses, CPU caches, and OS scheduling all introduce noise. BenchmarkDotNet handles all of this automatically and produces statistically reliable results.

Installing and First Benchmark

Add the NuGet package, create a class with [Benchmark] methods, and run with BenchmarkRunner.Run. Always run benchmarks in Release mode.

// dotnet add package BenchmarkDotNet

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

[MemoryDiagnoser]           // report allocations
[RankColumn]                // rank methods by speed
public class StringBenchmarks
{
    [Benchmark(Baseline = true)]
    public string Concatenation()
    {
        var s = "";
        for (int i = 0; i < 100; i++) s += i;
        return s;
    }

    [Benchmark]
    public string StringBuilder()
    {
        var sb = new System.Text.StringBuilder();
        for (int i = 0; i < 100; i++) sb.Append(i);
        return sb.ToString();
    }
}

// Program.cs (must run as Release):
BenchmarkRunner.Run<StringBenchmarks>();

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