Are you committing the composer.lock file in your projects? Likewise you should try and use as close to absolute version numbers as possible in your composer.js

Are you committing the composer.lock file in your projects? Likewise you should try and use as close to absolute version numbers as possible in your composer.json `requires` sections. I used did a quick test (having run `composer clearcache` each time) on one of my projects: Without composer.lock: Memory usage: 75.96MB (peak: 87.5MB), time: 38.54s With composer.lock: Memory usage: 7.47MB (peak: 8.99MB), time: 28.6s