Microsoft released the latest version of C# i.e. C#13 and now it allows params to be any of the collections supported by collection expressions rather than just arrays. So, I quickly wrote the benchmark code to test the performance and overall, it did improve the performance.

Here’s the code snippet and results for the single value test:

public class ParamsBenchmark{
    // Dummy methods to illustrate the params collections
    public int SumOld(params int[] numbers)
    {
        var sum = 0;
        foreach (var num in numbers)
        {
            sum += num;
        }
        return sum;
    }

    public int SumNew(params Span<int> numbers)
    {
        int sum = 0;
        foreach (var num in numbers)
        {
            sum += num;
        }
        return sum;
    }

    [Benchmark]
    public int SumOldParams()
    {
        return SumOld(1, 2, 3, 4, 5);
    }

    [Benchmark]
    public int SumNewParams()
    {
        return SumNew([1, 2, 3, 4, 5]);
    }
}

Below are my benchmark results: