Eminently pragmatic solution — I like it. In Rust, a crate is a compilation unit, and the compiler has limited parallelism opportunities, especially since rustc

Eminently pragmatic solution — I like it. In Rust, a crate is a compilation unit, and the compiler has limited parallelism opportunities, especially since rustc offloads much of the work to LLVM, which is largely single-threaded. It’s not surprising they didn’t see a linear speedup from splitting into so many crates. The compiler now produces a large number of intermediate object files that must be read back and linked into the final binary. On top of that, rustc caches a significant amount of semantic information — lifetimes, trait resolutions, type inference — much of which now has to be recomputed for each crate, including dependencies. That introduces a lot of redundant work. I also would expect this to hurt runtime performance as it likely reduces inlining opportunities (unless LTO is really good now?)