PHP Performance: if/elseif vs case/switch vs nested if

PHP Performance: if,elseif vs case,switch vs nested if.php

<?php
$iter = 500000;

$start = microtime(true);
$n = 0;
for ($c = 0; $c < 7 * $iter; $c++) {
    $i = $c % 16;

    if ($i === 0) {
        $n += 0;
    } elseif ($i === 1) {
        $n -= 1;
    } elseif ($i === 2) {
        $n -= 2;
    } elseif ($i === 3) {
        $n += 3;
    } elseif ($i === 4) {
        $n += 4;
    } elseif ($i === 5) {
        $n -= 5;
    } elseif ($i === 6) {
        $n -= 6;
    } elseif ($i === 7) {
        $n += 7;
    } elseif ($i === 8) {
        $n += 0;
    } elseif ($i === 9) {
        $n -= 1;
    } elseif ($i === 10) {
        $n -= 2;
    } elseif ($i === 11) {
        $n += 3;
    } elseif ($i === 12) {
        $n += 4;
    } elseif ($i === 13) {
        $n -= 5;
    } elseif ($i === 14) {
        $n -= 6;
    } elseif ($i === 15) {
        $n += 7;
    }

}

$result = microtime(true) - $start;
echo 'RESULT: ';
echo "$result (FLAT IF)\n";
// RESULT: 0.26509881019592 (FLAT IF)

$start = microtime(true);
$n = 0;
for ($c = 0; $c < 7 * $iter; $c++) {
    $i = $c % 16;

    switch ($i) {
        case 0:
            $n += 0;
            break;
        case 1:
            $n -= 1;
            break;
        case 2:
            $n -= 2;
            break;
        case 3:
            $n += 3;
            break;
        case 4:
            $n += 4;
            break;
        case 5:
            $n -= 5;
            break;
        case 6:
            $n -= 6;
            break;
        case 7:
            $n += 7;
            break;
        case 8:
            $n += 0;
            break;
        case 9:
            $n -= 1;
            break;
        case 10:
            $n -= 2;
            break;
        case 11:
            $n += 3;
            break;
        case 12:
            $n += 4;
            break;
        case 13:
            $n -= 5;
            break;
        case 14:
            $n -= 6;
            break;
        case 15:
            $n += 7;
            break;
    }
}

$result = microtime(true) - $start;
echo 'RESULT: ';
echo "$result (SWITCH CASE)\n";
// RESULT: 0.15897297859192 (SWITCH CASE)

$start = microtime(true);
$n = 0;
for ($c = 0; $c < 7 * $iter; $c++) {
    $i = $c % 16;
    if ($i < 8) {
        if ($i < 4) {
            if ($i < 2) {
                if ($i === 0) {
                    $n += 0;
                } else {
                    $n -= 1;
                }

            } else {
                if ($i === 2) {
                    $n -= 2;
                } else {
                    $n += 3;
                }

            }
        } else {
            if ($i < 6) {
                if ($i === 4) {
                    $n += 4;
                } else {
                    $n -= 5;
                }

            } else {
                if ($i === 6) {
                    $n -= 6;
                } else {
                    $n += 7;
                }

            }
        }
    } else {
        if ($i < 12) {
            if ($i < 10) {
                if ($i === 8) {
                    $n += 0;
                } else {
                    $n -= 1;
                }

            } else {
                if ($i === 10) {
                    $n -= 2;
                } else {
                    $n += 3;
                }

            }
        } else {
            if ($i < 14) {
                if ($i === 12) {
                    $n += 4;
                } else {
                    $n -= 5;
                }

            } else {
                if ($i === 14) {
                    $n -= 6;
                } else {
                    $n += 7;
                }

            }
        }
    }
}

$result = microtime(true) - $start;
echo 'RESULT: ';
echo "$result (NESTED IF)\n";
// RESULT: 0.13465404510498 (NESTED IF)