# Release 2.5 (2021-12-13)

- The garbage collector no longer blocks new builds, so the message `waiting for the big garbage collector lock...` is a thing of the past.

- Binary cache stores now have a setting `compression-level`.

- `nix develop` now has a flag `--unpack` to run `unpackPhase`.

- Lists can now be compared lexicographically using the `<` operator.

- New built-in function: `builtins.groupBy`, with the same functionality as Nixpkgs' `lib.groupBy`, but faster.

- `nix repl` now has a `:log` command.