@GromNaN suggested optimizing the PSR-0 autoloader.

See http://git.io/N7FFyQ
Composer: --prefer-source to avoid GitHub API rate-limiting.

GitHub imposes a limit on the number of requests/seconds to their API.
Unfortunately file downloads are considered API requests as well so a
project with a lot of Composer dependencies can quickly run out of
allowed API calls.
Composer likes to ask questions, shut it up.