This release has the following improvements: The Nix expression evaluator is now much faster in most cases: typically, 3 to 8 times compared to the old implementation. It also uses less memory. It no longer depends on the ATerm library. Support for configurable parallelism inside builders. Build scripts have always had the ability to perform multiple build actions in parallel (for instance, by running make -j 2), but this was not desirable because the number of actions to be performed in parallel was not configurable. Nix now has an option --cores N as well as a configuration setting build-cores = N that causes the environment variable NIX_BUILD_CORES to be set to N when the builder is invoked. The builder can use this at its discretion to perform a parallel build, e.g., by calling make -j N. In Nixpkgs, this can be enabled on a per-package basis by setting the derivation attribute enableParallelBuilding to true. nix-store -q now supports XML output through the --xml flag. Several bug fixes.