compare leveldb-daemon (https://github.com/mambaru/leveldb-daemon), memcached & redis through phpredis (https://github.com/nicolasff/phpredis) leveldb-daemon: ~34,6s memcached: ~6.5s redis: ~5.1s

gistfile1.php

<?php

set_include_path(get_include_path() . PATH_SEPARATOR . dirname(__FILE__));
include_once 'JsonRpc.php';
$config = include 'config.php';

$connect = new JsonRpc_Connection($config['host'], $config['port']);

$t1 = microtime(true);
for ($i = 0; $i < 10000; $i++) {
    $connect->request('set', array(
        'foo' => uniqid('foo'),
        'bar' => uniqid('bar'),
    ));
    $connect->process();

    $future = $connect->request('get', array('foo', 'bar'));
    $connect->process();

    $future = $connect->request('get', array('foo', 'bar'));
    $connect->process();

    $future = $connect->request('get', array('foo', 'bar'));
    $connect->process();

    $future = $connect->request('get', array('foo', 'bar'));
    $connect->process();
}
$t2 = microtime(true);

echo 'leveldb = ', ($t2-$t1), PHP_EOL;

//-------------------------------------------------

$memcache = new Memcache;
$memcache->connect('localhost', 11211);

$t1 = microtime(true);
for ($i = 0; $i < 10000; $i++) {
    $memcache->set('foo', uniqid('foo'));
    $memcache->set('bar', uniqid('bar'));

    $memcache->get(array('foo', 'bar'));
    $memcache->get(array('foo', 'bar'));
    $memcache->get(array('foo', 'bar'));
    $memcache->get(array('foo', 'bar'));
}
$t2 = microtime(true);

echo 'memcache = ', ($t2-$t1), PHP_EOL;

//-------------------------------------------------

$redis = new Redis();
$redis->connect('localhost', 6379);

$t1 = microtime(true);
for ($i = 0; $i < 10000; $i++) {
    $redis->mset(array(
        'foo' => uniqid('foo'),
        'bar' => uniqid('bar'),
    ));

    $redis->mGet(array('foo', 'bar'));
    $redis->mGet(array('foo', 'bar'));
    $redis->mGet(array('foo', 'bar'));
    $redis->mGet(array('foo', 'bar'));
}
$t2 = microtime(true);

echo 'redis = ', ($t2-$t1), PHP_EOL;