Method for running other XML methods through a performance test

RunPerformanceTest()

public static double RunPerformanceTest(string filePath, Action<string> performanceTestMethod)
{
    Stopwatch sw = new Stopwatch();

    int iterations = 50;
    double elapsedMilliseconds = 0;

    // Run the method 50 times to rule out any bias.
    for (var i = 0; i < iterations; i++)
    {
        sw.Restart();
        performanceTestMethod(filePath);
        sw.Stop();

        elapsedMilliseconds += sw.ElapsedMilliseconds;
    }

    // Calculate the average elapsed seconds per run
    double avergeSeconds = (elapsedMilliseconds / iterations) / 1000.0;

    return avergeSeconds;
}