The feature makes the navigation of pages with no-op service worker fetch handlers fast by skipping them. Some sites have a no-op (no operation) fetch listener (e.g. onfetch = () => {}). Since having the fetch listener was one of the requirements to be a progressive web app (PWA), we assume they did that to make their site recognized as PWA. However, it only brings overheads to start a service worker and execute a no-op listener without bringing any feature benefits like caching or offline capabilities because the code does nothing. To make the navigation to such pages faster, we would like to omit the service worker start and the listener dispatch from the navigation critical path if a user agent identifies that all the service worker's fetch listeners are no-ops. From version 112, Chromium starts to show console warnings if all the service worker’s fetch listeners are no-ops, and encourages developers to remove the useless fetch listeners. Hopefully sites stop using the useless fetch listeners and we can deprecate the feature in the future.
Some sites have a no-op (no operation) fetch handler (e.g. onfetch = () => {}). Since having the fetch handler was one of the requirements to be a progressive web app (PWA), we assume that they did that to make their site recognized as PWA. However, it only brings overheads to start a service worker and execute a no-op handler without bringing any feature benefits like caching or offline capabilities because the code does nothing.
Explainers: https://github.com/yoshisatoyanagisawa/service-worker-skip-no-op-fetch-handler