Parallel execution is being added to the Rust compiler front end to significantly reduce compile times, according to a November 9 announcement of the parallel rustc working group.
Currently in an experimental stage, the parallel front end is due to ship with the stable compiler next year. Developers can try parallel execution now by running the nightly compiler with the -Z threads=8 option. When the parallel front end is run in multi-threaded mode with -Z threads-8, measurements on “real world” code have shown that compile times can be reduced by as much as 50%. Effects vary widely based on characteristics of the code and the build configuration.