**Strict** — no cross-site send (best CSRF, breaks some OAuth flows).

Caching & Networking

SameSite cookie modes

<h2>Summary</h2>
<p><code>fetchpriority="high"</code> on LCP image; <code>low</code> on below-fold. Preload sets priority implicitly. Mis-prioritization starves LCP for decorative assets. Resource Timing API verifies actual priority (browser-dependent). Part of holistic critical path tuning.</p>
<h2>Code example</h2>
<pre><code class="language-html">&lt;img src="/hero.webp" fetchpriority="high" width="1200" height="630" alt="" /&gt;
&lt;img src="/avatar.png" fetchpriority="low" loading="lazy" alt="" /&gt;
</code></pre>
<h2>Key points</h2>
<ul>
<li><code>fetchpriority="high"</code> on LCP image; <code>low</code> on below-fold.</li>
<li>Preload sets priority implicitly.</li>
<li>Mis-prioritization starves LCP for decorative assets.</li>
<li>Resource Timing API verifies actual priority (browser-dependent).</li>
<li>Part of holistic critical path tuning.</li>
</ul>
<h2>Further reading</h2>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#fetchpriority">fetchpriority</a></li>
<li><a href="https://web.dev/articles/preload-critical-assets">Optimize resource loading</a></li>
</ul>
<h2>Related concepts</h2>
<ul>
<li><a href="/blogs/level-5-streaming-fetch-response-handling">Streaming fetch response handling</a></li>
<li><a href="/blogs/level-5-samesite-cookie-modes">SameSite cookie modes</a></li>
</ul>


`fetchpriority="high"` on LCP image; `low` on below-fold.

Priority hints

Read `response.body` reader incrementally — parse NDJSON/SSE/chunked HTML as bytes arrive.