Now, Composer is working on speeding that up, but we should trim the fat on our side. We are currently shipping with two CLIs, Drush and Drupal Console. We use Drupal Console in our docs, Drush is unused. So let's remove it to speed up the initial install. People who want it can add it to their composer.json (or they might already use a globally installed one).
https://github.com/composer/composer/pull/4961#issuecomment-189000045 shows that the current version of the template resolves to about 107 packages. If --prefer-source is used, that's 107 (slow) git clones.
Now, Composer is working on speeding that up, but we should trim the fat on our side. We are currently shipping with two CLIs, Drush and Drupal Console. We use Drupal Console in our docs, Drush is unused. So let's remove it to speed up the initial install. People who want it can add it to their composer.json (or they might already use a globally installed one).