TestGetComponent

void TestGetComponent()
{
    Stopwatch stopwatch = Stopwatch.StartNew();

    for (int i = 0; i < iterations; i++)
    {
        Camera.main.GetComponent<AudioListener>().enabled = true;
    }

    double getComponentTime = stopwatch.ElapsedMilliseconds;
    stopwatch.Reset();

    stopwatch.Start();
    AudioListener al = null;
    for (int i = 0; i < iterations; i++)
    {
        if (i == 0)
            al = Camera.main.GetComponent<AudioListener>();

        if (al != null)
            al.enabled = true;
    }
    double getComponentOnce = stopwatch.ElapsedMilliseconds;
    stopwatch.Reset();

    Debug.LogFormat(
        "GetComponent test results:\n" +
        "total GetComponent time: {0:G}ms\n" +
        "average GetComponent time: {1:G}ms\n" +
        "total single GetComponent time: {2:G}ms\n" +
        "average single GetComponent time: {3:G}ms\n",
        getComponentTime,
        (getComponentTime / iterations),
        getComponentOnce,
        (getComponentOnce / iterations)
        );
}