Thanks for commenting, this is a cool experiment I worked on, just trying to eliminate the bootstrapping delay. Will be happy to answer any questions here, via issues in the demo repos (https://github.com/bahmutov/instant-vdom-todo), or in the library repo https://github.com/bahmutov/bottle-service
The demo itself runs from https://instant-todo.herokuapp.com/ (please use Chrome or Opera or enable ServiceWorker in the Firefox for now)
PS: Here is a little bonus, my current exploration where ServiceWorker might be useful - run your server (like ExpressJS) inside the ServiceWorker ;) https://github.com/bahmutov/express-service