BenchmarkDotNet

--------:| | RunParallel | 381.8 us | | Run | 412.2 us | .NET 5 - .NET 6 -> ~5% .NET 5 - .NET 6 PGO -> ~20% Here is what I learned from micro-optimizing a .NET application: - Use BenchmarkDotNet[0] for general measurements and Visual Studio profiler tools for detailed inspection. They help a lot. - Memory allocations matter. Using capturing lambdas, LINQ, even foreach on interfaces introduce allocations and slows down the application. You can use ClrHeapAllocationAnalyzer[1] to find these hidden allocations. - Using abstractions with interfaces and casting back to concrete types cause some overhead, though PGO will probably eliminate most of these. - Use LINQ cautiously as its variants are mostly slower than explicit coding. E.g. .Any() vs .Count == 0 - Checking Logger.IsEnabled() before calling Logger.Debug() etc. helps a lot. You can even automate this with Fody [2], but it breaks Edit&Continue and possibly .NET Hot Reload too, so it may hinder your productivity. [0] https://github.com/dotnet/BenchmarkDotNet [1] https://github.com/microsoft/RoslynClrHeapAllocationAnalyzer [2] https://github.com/jorisdebock/LoggerIsEnabled.Fody