WPT details: https://github.com/web-platform-tests/wpt/tree/master/loading/early-hints
Support 103 Early Hints informational responses during top-level frame navigation. When a 103 response includes link headers Chromium tries to preload specified resources (including modulepreload) or preconnect to specified origins before the final response is received. This gives Web developers a way to optimize Core Web Vitals such as Largest Contentful Paint (LCP).
A few months ago, we announced a collaborative experiment [1] to measure the potential impact of 103 early hints. The results indicate that Early Hints could result in speed improvements on the order of a few hundred milliseconds (the sample size is a bit small though). Given these encouraging results, we are now moving forward with the next steps, starting with this intent to prototype. [1] https://chromium.googlesource.com/chromium/src/+/master/docs/early-hints.md
Docs: https://docs.google.com/document/d/1gCh_CnfrJq_VL7aGoq6skc7sn4yn5pKsM0gkHe5B9go/edit?usp=sharing
Samples: https://early-hints.fastlylabs.com/
Explainers: https://github.com/bashi/early-hints-explainer/blob/main/explainer.md