I guess I should open a github issue or send a PR. The way to make Zingo-PC faster is to compile the Rust/node binding (neon) with --release flag. i.e.:
In package.json change from this:
"neon": "cargo-cp-artifact -a cdylib zingolib-native src/native.node -- cargo build --manifest-path native/Cargo.toml --message-format=json-render-diagnostics"
to this:
"neon": "cargo-cp-artifact -a cdylib zingolib-native src/native.node -- cargo build --release --manifest-path native/Cargo.toml --message-format=json-render-diagnostics"