Okay here's my findings • v2.10.1rc0, no VCS, lockfile from pip-tools, export takes 43 seconds. Running immediately after and it takes 20 seconds. Ran again and it takes 1 second each successive time. • v2.10.1rc0, with VCS, lockfile from pip-tools, export takes 2m30s. Running immediately after and it takes 22 seconds. Running again takes 1 second and all successive runs take that long. okay so VCS isn't the issue (though weird that it takes three runs to reach its best caching). • v2.11.0, with VCS, lockfile from pants with pex, export takes 58 seconds. Running again takes 41 seconds. Again at 38 seconds. Again up to 1m2s. Again 46 so doesn't seem like it's converging like it used to. • v2.11.0, no VCS, lockfile from pants with pex, export takes 1m7s. Running again takes 48 seconds. Again at 46 seconds. Doesn't show signs of converging. Okay so 2.11 changes things but unclear if it's 2.11 or pex lockfile. Revert back to pip-tools controlled lockfile and see what happens. • v2.11.0, no VCS, lockfile from pip-tools, export takes 2m50s (a lot of time installing constraints file). Running again is 47 seconds and that seems to continue indefinitely. saving sanity and going to assume adding back VCS doesn't make it better. So I'm fairly confident it's just the change from 2.10 to 2.11.