rust-cargo-fast-iteration-profile

Speed up Rust development iteration when cargo build --release takes 10+ minutes even for one-line edits. Use when: (1) every release rebuild takes minutes despite tiny edits, (2) Cargo.toml has lto = "fat" and/or codegen-units = 1 in [profile.release], (3) you want a production — shaped build for testing without paying the LTO cost on every iteration, (4) you suspect cargo is re-linking the whole binary instead of…