Tried on https://github.com/snipsco/rustling-ontology which has historically be a huge source of pain.
10/10 13:02 ~/dev/snips/rustling-ontology% cargo build --release
Finished release [optimized] target(s) in 1110.76 secs
10/10 13:24 ~/dev/snips/rustling-ontology% cargo +nightly build --release
Finished release [optimized] target(s) in 1036.68 secs
10/10 13:48 ~/dev/snips/rustling-ontology% RUSTFLAGS='-C codegen-units=16 -Z thinlto' cargo +nightly build --release
Finished release [optimized] target(s) in 401.22 secs
Runtime Benches show no measurable impact.
Congrats !