Sarcasm aside, the Rust compiler has gotten a lot faster (and parallelizes better) over the last year thanks to Nicolas Nethercote and others.

Another thing few people realize is that the "incremental" compilation mode that's the default for debug builds can also be enabled for release builds!

In CI, something like sccache can help a lot (using the GCS or S3 backend). It makes GitHub Actions' two-core limit almost bearable. Almost.