Benchmark newInstanceWithoutConstructor vs unserialize for object creation vs json

results

PHP 5.6.29:
    ReflectionClass::newInstanceWithoutConstructor: 0.17457699775696
    ReflectionClass::newInstanceWithoutConstructor(json): 0.11926913261414
    unserialize: 0.21122980117798

    
PHP 7.1.0:
    ReflectionClass::newInstanceWithoutConstructor: 0.066795110702515
    ReflectionClass::newInstanceWithoutConstructor(json): 0.065139055252075
    unserialize: 0.10229301452637

test.php

<?php

class Foo implements \Serializable
{
    protected $a;
    protected $b;

    public function __construct($a, $b)
    {
        $this->a = $a;
        $this->b = $b;
    }

    public function serialize()
    {
        return serialize([$this->a, $this->b]);
    }

    public function unserialize($data)
    {
        list($this->a, $this->b) = unserialize($data);
    }
}

class FooSub extends Foo
{
}

class FooJson extends Foo
{
    public function serialize()
    {
        return json_encode([$this->a, $this->b]);
    }

    public function unserialize($data)
    {
        list($this->a, $this->b) = json_decode($data, true);
    }
}

$fooObj = new FooSub(123.4, 'Hello');
$serializeObjStr = serialize($fooObj);
$serializeDataStr = $fooObj->serialize();
$fooJsonObj = new FooJson(123.4, 'Hello');
$serializeJsonDataStr = $fooJsonObj->serialize();

echo 'ReflectionClass::newInstanceWithoutConstructor: ';
$r = new ReflectionClass(FooSub::class);
$start = microtime(true);
for ($i = 1; $i < 100000; $i++) {
    $obj = $r->newInstanceWithoutConstructor();
    $obj->unserialize($serializeDataStr);
}
$now = microtime(true);
echo ($now - $start) . PHP_EOL;

echo 'ReflectionClass::newInstanceWithoutConstructor(json): ';
$r = new ReflectionClass(FooJson::class);
$start = microtime(true);
for ($i = 1; $i < 100000; $i++) {
    $obj = $r->newInstanceWithoutConstructor();
    $obj->unserialize($serializeJsonDataStr);
}
$now = microtime(true);
echo ($now - $start) . PHP_EOL;

echo 'unserialize: ';
$start = microtime(true);
for ($i = 1; $i < 100000; $i++) {
    $obj = unserialize($serializeObjStr);
}
$now = microtime(true);
echo ($now - $start) . PHP_EOL;