Today Composer released v2.0 which included many changes and performance improvements:

We overhauled pretty much everything from the protocol used between Composer and to the dependency resolution, including downloading files in parallel using curl and constraint evaluation optimizations. This leads to massive improvements in terms of both speed and memory usage. The difference depends on your use case, so while I’ve seen reports of improvements of over 50% to both in some projects, I cannot put an exact number on it. But I am sure you will be positively surprised if you haven’t tried Composer 2 yet.

Updating to 2.0 is pretty straight forward and based on my initial testing feels much faster and doesn’t consume as much memory as its predecessor. Updating is also pretty easy and here is the steps outlined in their initial announcement:

 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.

Be sure to check out their official announcement for more details and changelog.