Enum.GetValues: cast vs. no cast to typed array test.

EnumGetValuesTest.cs

// Intel(R) Core(TM) i7-2600 CPU @ 3.40 GHz 3.40 GHz
// 16 GB RAM, Windows 7, 64 bit
//
//No cast:0.854751600000001 +- 0.182965645566156ms
//Cast:0.724137 +- 0.148216330378943ms

// Conclusion: Cast is indeed faster, but remember that we are talking here about _miliseconds_
// for 1000 enumerations of an enum with 1000 elements. First verify whether this is really significant in your code, before
// proceeding with micro-optimizations.
// Context: http://stackoverflow.com/a/105402/2642204

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

namespace EnumTest
{
    public class Program
    {
        enum E
        {
            V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, V11, V12, V13, V14, V15, V16, V17, V18, V19, V20, V21, V22, V23, V24, V25, V26, V27, V28, V29, V30, V31, V32,
            V33, V34, V35, V36, V37, V38, V39, V40, V41, V42, V43, V44, V45, V46, V47, V48, V49, V50, V51, V52, V53, V54, V55, V56, V57, V58, V59, V60, V61, V62,
            V63, V64, V65, V66, V67, V68, V69, V70, V71, V72, V73, V74, V75, V76, V77, V78, V79, V80, V81, V82, V83, V84, V85, V86, V87, V88, V89, V90, V91, V92,
            V93, V94, V95, V96, V97, V98, V99, V100, V101, V102, V103, V104, V105, V106, V107, V108, V109, V110, V111, V112, V113, V114, V115, V116, V117, V118,
            V119, V120, V121, V122, V123, V124, V125, V126, V127, V128, V129, V130, V131, V132, V133, V134, V135, V136, V137, V138, V139, V140, V141, V142, V143,
            V144, V145, V146, V147, V148, V149, V150, V151, V152, V153, V154, V155, V156, V157, V158, V159, V160, V161, V162, V163, V164, V165, V166, V167, V168,
            V169, V170, V171, V172, V173, V174, V175, V176, V177, V178, V179, V180, V181, V182, V183, V184, V185, V186, V187, V188, V189, V190, V191, V192, V193,
            V194, V195, V196, V197, V198, V199, V200, V201, V202, V203, V204, V205, V206, V207, V208, V209, V210, V211, V212, V213, V214, V215, V216, V217, V218,
            V219, V220, V221, V222, V223, V224, V225, V226, V227, V228, V229, V230, V231, V232, V233, V234, V235, V236, V237, V238, V239, V240, V241, V242, V243,
            V244, V245, V246, V247, V248, V249, V250, V251, V252, V253, V254, V255, V256, V257, V258, V259, V260, V261, V262, V263, V264, V265, V266, V267, V268,
            V269, V270, V271, V272, V273, V274, V275, V276, V277, V278, V279, V280, V281, V282, V283, V284, V285, V286, V287, V288, V289, V290, V291, V292, V293,
            V294, V295, V296, V297, V298, V299, V300, V301, V302, V303, V304, V305, V306, V307, V308, V309, V310, V311, V312, V313, V314, V315, V316, V317, V318,
            V319, V320, V321, V322, V323, V324, V325, V326, V327, V328, V329, V330, V331, V332, V333, V334, V335, V336, V337, V338, V339, V340, V341, V342, V343,
            V344, V345, V346, V347, V348, V349, V350, V351, V352, V353, V354, V355, V356, V357, V358, V359, V360, V361, V362, V363, V364, V365, V366, V367, V368,
            V369, V370, V371, V372, V373, V374, V375, V376, V377, V378, V379, V380, V381, V382, V383, V384, V385, V386, V387, V388, V389, V390, V391, V392, V393,
            V394, V395, V396, V397, V398, V399, V400, V401, V402, V403, V404, V405, V406, V407, V408, V409, V410, V411, V412, V413, V414, V415, V416, V417, V418,
            V419, V420, V421, V422, V423, V424, V425, V426, V427, V428, V429, V430, V431, V432, V433, V434, V435, V436, V437, V438, V439, V440, V441, V442, V443,
            V444, V445, V446, V447, V448, V449, V450, V451, V452, V453, V454, V455, V456, V457, V458, V459, V460, V461, V462, V463, V464, V465, V466, V467, V468,
            V469, V470, V471, V472, V473, V474, V475, V476, V477, V478, V479, V480, V481, V482, V483, V484, V485, V486, V487, V488, V489, V490, V491, V492, V493,
            V494, V495, V496, V497, V498, V499, V500, V501, V502, V503, V504, V505, V506, V507, V508, V509, V510, V511, V512, V513, V514, V515, V516, V517, V518,
            V519, V520, V521, V522, V523, V524, V525, V526, V527, V528, V529, V530, V531, V532, V533, V534, V535, V536, V537, V538, V539, V540, V541, V542, V543,
            V544, V545, V546, V547, V548, V549, V550, V551, V552, V553, V554, V555, V556, V557, V558, V559, V560, V561, V562, V563, V564, V565, V566, V567, V568,
            V569, V570, V571, V572, V573, V574, V575, V576, V577, V578, V579, V580, V581, V582, V583, V584, V585, V586, V587, V588, V589, V590, V591, V592, V593,
            V594, V595, V596, V597, V598, V599, V600, V601, V602, V603, V604, V605, V606, V607, V608, V609, V610, V611, V612, V613, V614, V615, V616, V617, V618,
            V619, V620, V621, V622, V623, V624, V625, V626, V627, V628, V629, V630, V631, V632, V633, V634, V635, V636, V637, V638, V639, V640, V641, V642, V643,
            V644, V645, V646, V647, V648, V649, V650, V651, V652, V653, V654, V655, V656, V657, V658, V659, V660, V661, V662, V663, V664, V665, V666, V667, V668,
            V669, V670, V671, V672, V673, V674, V675, V676, V677, V678, V679, V680, V681, V682, V683, V684, V685, V686, V687, V688, V689, V690, V691, V692, V693,
            V694, V695, V696, V697, V698, V699, V700, V701, V702, V703, V704, V705, V706, V707, V708, V709, V710, V711, V712, V713, V714, V715, V716, V717, V718,
            V719, V720, V721, V722, V723, V724, V725, V726, V727, V728, V729, V730, V731, V732, V733, V734, V735, V736, V737, V738, V739, V740, V741, V742, V743,
            V744, V745, V746, V747, V748, V749, V750, V751, V752, V753, V754, V755, V756, V757, V758, V759, V760, V761, V762, V763, V764, V765, V766, V767, V768,
            V769, V770, V771, V772, V773, V774, V775, V776, V777, V778, V779, V780, V781, V782, V783, V784, V785, V786, V787, V788, V789, V790, V791, V792, V793,
            V794, V795, V796, V797, V798, V799, V800, V801, V802, V803, V804, V805, V806, V807, V808, V809, V810, V811, V812, V813, V814, V815, V816, V817, V818,
            V819, V820, V821, V822, V823, V824, V825, V826, V827, V828, V829, V830, V831, V832, V833, V834, V835, V836, V837, V838, V839, V840, V841, V842, V843,
            V844, V845, V846, V847, V848, V849, V850, V851, V852, V853, V854, V855, V856, V857, V858, V859, V860, V861, V862, V863, V864, V865, V866, V867, V868,
            V869, V870, V871, V872, V873, V874, V875, V876, V877, V878, V879, V880, V881, V882, V883, V884, V885, V886, V887, V888, V889, V890, V891, V892, V893,
            V894, V895, V896, V897, V898, V899, V900, V901, V902, V903, V904, V905, V906, V907, V908, V909, V910, V911, V912, V913, V914, V915, V916, V917, V918,
            V919, V920, V921, V922, V923, V924, V925, V926, V927, V928, V929, V930, V931, V932, V933, V934, V935, V936, V937, V938, V939, V940, V941, V942, V943,
            V944, V945, V946, V947, V948, V949, V950, V951, V952, V953, V954, V955, V956, V957, V958, V959, V960, V961, V962, V963, V964, V965, V966, V967, V968,
            V969, V970, V971, V972, V973, V974, V975, V976, V977, V978, V979, V980, V981, V982, V983, V984, V985, V986, V987, V988, V989, V990, V991, V992, V993,
            V994, V995, V996, V997, V998, V999, V1000
        }

        static void Main(string[] args)
        {
            const int IterationCount = 1000;

            Warmup(IterationCount);

            Action noCastCall = () => TestNoCast();
            Action castCall = () => TestCast();

            Stopwatch sw = new Stopwatch();

            var noCast = Enumerable
                .Range(0, IterationCount)
                .Select(i => Measure(sw, noCastCall))
                .ToArray();

            var cast = Enumerable
                .Range(0, IterationCount)
                .Select(i => Measure(sw, castCall))
                .ToArray();

            var noCastAvg = Average(noCast);
            var castAvg = Average(cast);
            var noCastStdDev = StandardDeviation(noCastAvg, noCast);
            var castStdDev = StandardDeviation(castAvg, cast);

            Console.WriteLine("No cast:" + noCastAvg + " +- " + noCastStdDev + "ms");
            Console.WriteLine("Cast:" + castAvg + " +- " + castStdDev + "ms");
            Console.ReadKey();
        }

        static void Warmup(int iterationCount)
        {
            foreach (var x in Enumerable.Range(0, iterationCount))
            {
                TestNoCast();
                TestCast();
                TestCast();
                TestNoCast();
            }
        }

        static double Average(double[] values)
        {
            return 1.0 * values.Sum() / values.Length;
        }

        static double StandardDeviation(double average, double[] values)
        {
            return Math.Sqrt(values.Select(x => (x - average) * (x - average)).Sum() / values.Length);
        }

        static double Measure(Stopwatch sw, Action a)
        {
            sw.Reset();
            sw.Start();
            a();
            sw.Stop();
            return sw.Elapsed.TotalMilliseconds;
        }

        static void TestNoCast()
        {
            foreach (E e in Enum.GetValues(typeof(E)))
            {
                DummyFunction(e);
            }
        }

        static void TestCast()
        {
            foreach (var e in (E[])Enum.GetValues(typeof(E)))
            {
                DummyFunction(e);
            }
        }

        static int dummy = 0;

        static void DummyFunction(E e)
        {
            if (e.ToString().Contains('1'))
            {
                ++dummy;
            }
        }
    }
}

Thanks for looking into this. Your results are interesting and your analysis is very thorough. I've updated the gist, and the conclusion. IMHO this still qualifies as a micro-optimization that's not worth your time. Although I agree that it is good to know, that using the cast consistently produces faster code, and it might be important in some applications.