Neon is for creating native Node modules in rust, which are libraries that use the Node addon API [1].<p>node-ffi seems to be for adding a bridge between an existing non-Node module dynamic library and node, which at the very least seems to incur some non-negligible overhead; see the &quot;Call Overhead&quot; section of your link.<p>[1]: <a href="https:&#x2F;&#x2F;nodejs.org&#x2F;api&#x2F;addons.html" rel="nofollow">https:&#x2F;&#x2F;nodejs.org&#x2F;api&#x2F;addons.html</a>