Linq Concat Benchmark

linq-concat-benchmark.cs

static void Main(string[] args)
{
    Stopwatch sw = new Stopwatch();
    int count;
    IEnumerable<int> vals;

    int k = 1000000;
    for (int loops = 0; loops < 6; loops++)
    {
        Console.WriteLine($"Run {loops}");

        vals = Enumerable.Range(0, k);
        count = 0;
        sw.Restart();
        foreach (int i in vals)
            count++;
        double t1 = sw.Elapsed.TotalMilliseconds;
        Console.WriteLine($"Vanilla: {count} in {t1}ms");

        vals = Enumerable.Range(0, 2 * k);
        count = 0;
        sw.Restart();
        foreach (int i in vals)
            count++;
        double t2 = sw.Elapsed.TotalMilliseconds;
        Console.WriteLine($"Vanilla: {count} in {t2}ms");

        vals = Enumerable.Range(0, k).Concat(Enumerable.Range(0, k));
        count = 0;
        sw.Restart();
        foreach (int i in vals)
            count++;
        double t3 = sw.Elapsed.TotalMilliseconds;
        Console.WriteLine($"Concat:  {count} in {t3}ms (factor: {t3/t2:N2})");

        k = 2 * k;

        Console.WriteLine();

        GC.Collect();
        GC.WaitForPendingFinalizers();
        GC.Collect();
    } // for( loops )
} // Main( )

Results:

• Release mode
• Without debugging
• Using .Net 4.6.1