Updated pex to 2.66.0

[sureshjoshi]

Among other things, this comes with pip 25.3, which could lead to lockfile generation performance improvements (with some potential configuration changes):

pex-tool/pex#2968

[jsirois]

There are no configuration changes besides using --pip-version {25.3,latest,latest-compatible}. The Pip 25.3 speed bump only applies to --dry-run installs which Pex switched to by default in Pex 2.64.0 (The --avoid-downloads option, which defaults on for every Pip save vendored aka 20.3.4).

N.B.: For every second saved locking, that second awaits you when later using the lock and downloading. So the speedup is only for "lock engineering" and not overall. Overall (lock create + use lock to do something) is a wash.

[jsirois]

This is not True. You can use Pip 25.3 but Pex does not default to it unless you use --pip-version {latest,latest-compatible}, which I think Pants itself does, perhaps confusing you here.

[sureshjoshi]

Oh, yeah, re-wrote that twice and confused myself - to different audiences. Pants gets the auto-25.3 because we use latest, and for users I meant to tack it on to the "includes support" previous part of the sentence

[sureshjoshi]

N.B.: For every second saved locking, that second awaits you when later using the lock and downloading. So the speedup is only for "lock engineering" and not overall. Overall (lock create + use lock to do something) is a wash.

Yep