Why is PHP Composer so slow?

Question

Why is PHP Composer so slow when all I do is init a project with zero dependencies? Here are the commands I run:

composer init

Answer 1

The same here. Get more details with "composer install --profile -vvv". In my case it takes a long time to download a few JSON files. They get cached on my server, but they are still downloaded with every Composer update/install call.

... 30 minutes later ...

It looks like some performance problem @packagist.org. Now the Composer install runs within 2 seconds! And downloaded JSON files are properly cached.