I'm not sure how it compares, but an alpha for Composer 2.0 was released last week[1] and the release notes seem to imply that it runs in parallel by default now.
> Added support for parallel downloads of package metadata and zip files, this requires that the curl extension is present and we thus strongly recommend enabling curl
Yeah, using prestissimo makes package installation sooooo much faster. My Laravel project with over 100 dependencies downloads in under a minute, where it was like... 10 minutes before
