Inspired by this tweet https://twitter.com/clemensv/status/722821904189362179

ExceptionBenchmarks.cs

[Config(typeof(Config))]
public class Program
{
    static void Main(string[] args)
    {
        var summary = BenchmarkRunner.Run<Program>();
    }

    private class Config : ManualConfig
    {
        public Config()
        {
            Add(Job.Clr.WithLaunchCount(1));
            Add(new GCDiagnoser());
        }
    }
    
    // Yeah I know, *mutable* structs are BAD!!!!
    public struct ResultAndErrorCode<T>
    {
        public T Result;
        public int ErrorCode;
    }

    [Benchmark(Baseline = true)]
    public ResultAndErrorCode<string> ErrorCodeWithReturnValue()
    {
        var result = new ResultAndErrorCode<string>();
        result.Result = null;
        result.ErrorCode = 5;
        return result;
    }

    [Benchmark]
    public string ThrowExceptionGetMessage()
    {
        try
        {
            throw new InvalidOperationException("Benchmark");
        }
        catch (InvalidOperationException ioex)
        {
            // Only get the simple message from the Exception (don't trigger a StackTrace collection)
            return ioex.Message;
        }
    }

    [Benchmark]
    public string ThrowExceptionGetStackTrace()
    {
        try
        {
            throw new InvalidOperationException("Benchmark");
        }
        catch (InvalidOperationException ioex)
        {
            // Force collection of a full StackTrace
            return ioex.StackTrace;
        }
    }
}

Results:

Updated results (now with a "baseline" comparison of error codes):