v134 · performance

Document-Policy: expect-no-linked-resources

The expect-no-linked-resources configuration point in Document Policy allows a document to hint to the user agent to better optimize its loading sequence, such as not using the default speculative parsing behavior. User Agents have implemented speculative parsing of HTML to speculatively fetch resources that are present in the HTML markup, to speed up pag

concepts

  1. expect-no-linked-resources

    A Document-Policy that asserts a page declares zero <link> resources. Reduces fingerprinting surface.

  2. SPA shell measurement

    The explainer’s named target: tiny SPA shells. Model the parse cost saved when speculative HTML pre-parsing is skipped at different shell sizes.

  3. Policy Bundle Builder

    Page-profile tool. Punch in HTML size + link / script / inline counts, get a verdict on whether the hint is safe, estimated savings, and the exact header.

  4. Header Impact Explorer

    Pick a page archetype (SPA shell, API fragment, blog post, news homepage, e-commerce PDP) and see whether the policy is safe to deploy, which <link> resources would violate it, and the exact response header.

why it shipped

User Agents have implemented speculative parsing of HTML to speculatively fetch resources that are present in the HTML markup, to speed up page loading. For the vast majority of pages on the Web that have resources declared in the HTML markup, the optimization is beneficial and the cost paid in determining such resources is a sound tradeoff. However, the following scenarios might result in a sub-optimal performance tradeoff vs. the explicit time spent parsing HTML for determining sub resources to fetch:

references