symfony2 – 为什么更新composer中的依赖是如此缓慢？

我有问题，当我添加新的bundle到composer.json并执行它显示关于更新依赖关系和下一次下载它们的消息的时间非常低。

我有这个数据在composer.json(见下文)，执行时间约为20分钟！互联网连接是足够快，我可以下载大文件非常快…

有什么技巧使它更快？

{
"name": "symfony/framework-standard-edition","description": "The "Symfony Standard Edition" distribution","autoload": {
    "psr-0": { "": "src/" }
},"require": {
    "php": ">=5.3.3","symfony/symfony": "2.1.*","doctrine/orm": ">=2.2.3,<2.4-dev","doctrine/doctrine-bundle": "1.0.*","twig/extensions": "1.0.*","symfony/assetic-bundle": "2.1.*","symfony/swiftmailer-bundle": "2.1.*","symfony/monolog-bundle": "2.1.*","sensio/distribution-bundle": "2.1.*","sensio/framework-extra-bundle": "2.1.*","sensio/generator-bundle": "2.1.*","jms/security-extra-bundle": "1.2.*","jms/di-extra-bundle": "1.1.*","doctrine/doctrine-fixtures-bundle": "dev-master","webignition/doctrine-migrations-bundle": "dev-master"
},"scripts": {
    "post-install-cmd": [
        "SensioBundleDistributionBundleComposerScriptHandler::buildBootstrap","SensioBundleDistributionBundleComposerScriptHandler::clearCache","SensioBundleDistributionBundleComposerScriptHandler::installAssets","SensioBundleDistributionBundleComposerScriptHandler::installRequirementsFile"
    ],"post-update-cmd": [
        "SensioBundleDistributionBundleComposerScriptHandler::buildBootstrap","SensioBundleDistributionBundleComposerScriptHandler::installRequirementsFile"
    ]
},"minimum-stability": "dev","extra": {
    "symfony-app-dir": "app","symfony-web-dir": "web"
}