The https://blog.rust-lang.org/2023/06/01/Rust-1.70.0.html Thursday, and users should see “substantially improved performance” when fetching information from the crate.io index. That’s because this release makes Cargo’s “sparse” protocol enabled by default for reading the index from crates.io.
It comes with a caveat, though — the upgrade changes the path to the crate cache, so dependencies must be downloaded again. The Rust team suggested developers clear out the old registry paths once they’ve fully committed to using the sparse protocol.
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