The new borrow checker is not yet all that fast. For instance, it was 5000x slower, according to a recent report. https://users.rust-lang.org/t/polonius-is-mor

The new borrow checker is not yet all that fast. For instance, it was 5000x slower, according to a recent report. https://users.rust-lang.org/t/polonius-is-more-ergonomic-than-nll-but-why-hasn-t-it-been-integrated-into-the-stable-or-nightly-channels-yet/129749/4 https://users.rust-lang.org/t/polonius-is-more-ergonomic-tha... >I recommend watching the video @nerditation linked. I believe Amanda mentioned somewhere that Polonius is 5000x slower than the existing borrow-checker; IIRC the plan isn't to use Polonius instead of NLL, but rather use NLL and kick off Polonius for certain failure cases.