$ composer require symfony/symfony:\*

$ rm -fr ~/.composer/cache/repo/
$ composer update --dry-run --profile --no-plugins
 :
Memory usage: 92.4MB (peak: 111.41MB), time: 139.99s

$ rm -fr ~/.composer/cache/repo/
$ composer update --dry-run --profile
 :
Memory usage: 92.61MB (peak: 111.62MB), time: 67.21s

$ git clone https://github.com/ngyuki/composer-curl-plugin.git
$ cd composer-curl-plugin

$ composer install

$ misc/composer.php global require ngyuki/composer-curl-plugin:dev-master

$ sudo tcpdump -nn 'host 87.98.253.214 and (tcp[tcpflags] & 255 == tcp-syn)'

$ misc/composer.php require symfony/symfony:\*

$ rm -fr cache/repo/
$ misc/composer.php update --dry-run --profile --no-plugins -vvv

$ rm -fr cache/repo/
$ misc/composer.php update --dry-run --profile -vvv