@Seba7890 Unless you use workers, JavaScript in browsers runs only on one thread anyway. What's the motivation behind keeping all the requests asynchronous?
DSF (in SBC mode with RaspPi) pushes over object model changes using a WebSocket so there is less overhead. Also note that there is a generic connector library available both for standalone and SBC mode, see https://www.npmjs.com/package/@duet3d/connectors You could use that as well in both cases.