Congratulations to the contributors of pip that made this release possible with various improvements! My heart is filled with warmth, pride and childlike joy to be part of this process!
While other features, optimizations and bug fixes are really well documented, the fast-deps exprimental feature is not quite. Despite its name, at the time of writing, for most of the cases (where the wheels are small) it does not make the pip install/pip download process any faster. The only case that it might be an optimization is where pip runs into a lot of dependencies conflicts and has to perform a series of backtracking. Edit: see also GH-8670.
Because of this, for the moment this unstable feature is only enabled when the 2020-resolver is used. In order to do so, invoke pip using pip --use-feature=2020-resolver --use-feature=fast-deps ... or (highly unrecommended) pip config edit with
[global]
use-feature =
2020-resolver
fast-deps
The purpose of my call for help on testing is solely to discover issues that slipped through the test suit as well as the peer reviewing process. I really appreciate any early input, as it will help me not only correcting my model but also save me from creating burden on the work of the pip team.