composer install or
composer update on your Drupal 8 installation to install or update modules and themes could be sometimes frustrating because it can be very slow. Too slow in fact. But it doesn't have to be that way. Here are some tips to speed your Composer working with Drupal.
Prestismo is a global composer plugin that that enables parallel installations and it's very fast! It can be more than 2x faster. But Prestissimo requires cURL, which may not work behind certain firewalls or proxies.
To install prestissimo follow these steps: