This week have been marked by the release of Composer 2.0, the dependency manager for PHP. This is a major release with over 50 new features and bugfixes. Top new feature in the change list is the performance improvement from Composer 1.0 to 2.0 which could reach over 50% on some projects.
Upgrade to Composer 2.0 should be smooth and swift, most commands and arguments remain unchanged, and composer.lock files are interoperable between versions. So you could be easily switch back in case there are any issues.
If you run
composer self-update from 1.x, it will warn you that a new stable major version of Composer is available, and you can use
composer self-update --2 to migrate to it.
Should you encounter issues, you can go back at any time by using
composer self-update --1. Hopefully that will make everyone feel comfortable to experiment with the new release.
Most issues will be noticed related to plugins. Plugins need to be updated to support Composer 2, and some of them are not ready, yet. Composer 2 will complain and fail to resolve dependencies if a plugin does not support it, so no need to overthink it, you can try it out and see how it goes.