diff --git a/docs/architecture/performance-journeys.md b/docs/architecture/performance-journeys.md
index bde842eb0..4e1a35629 100644
--- a/docs/architecture/performance-journeys.md
+++ b/docs/architecture/performance-journeys.md
@@ -32,16 +32,19 @@ The bytes a browser fetches before Angular can bootstrap, read from the built
 - every `<link rel="stylesheet">`,
 - every `<link rel="modulepreload">` chunk.
 
-Manifest, icons, external URLs and lazy chunks are not counted. A file that
-`index.html` references but the build did not emit is an error, never zero
-bytes. The value is raw (uncompressed) size, which is what the renderer parses;
-it matches the "Initial total" line of the Angular build output.
+Manifest, icons, external URLs, commented-out tags and lazy chunks are not
+counted. A file that `index.html` references but the build did not emit is an
+error, never zero bytes. The value is raw (uncompressed) size, which is what the
+renderer parses. It is Angular's "Initial total" plus `index.html` and
+`assets/app-config.js` (about 4 KB together), so it sits slightly above the
+rounded figure the build prints; never copy that figure into a baseline, use
+the script's output.
 
 ```bash
-pnpm nx build web                       # production configuration
-pnpm run perf:initial-bytes             # human-readable breakdown
-pnpm run perf:initial-bytes -- --json   # machine-readable breakdown
-pnpm run perf:initial-bytes -- --summary dist/performance/journey-summary.json
+pnpm nx build web                                # production configuration
+pnpm run perf:initial-bytes                      # human-readable breakdown
+pnpm --silent run perf:initial-bytes -- --json   # machine-readable; --silent keeps pnpm's headers out of stdout
+node tools/performance/measure-initial-bytes.mjs --summary dist/performance/journey-summary.json
 ```
 
 `--summary` writes the journey summary shape (`journeys.<journey>.counters`)
diff --git a/tools/performance/measure-initial-bytes.mjs b/tools/performance/measure-initial-bytes.mjs
index c3cb6067f..17f734c3c 100644
--- a/tools/performance/measure-initial-bytes.mjs
+++ b/tools/performance/measure-initial-bytes.mjs
@@ -21,6 +21,8 @@ export const INITIAL_BYTES_COUNTER = 'renderer.initialBytes';
 export const LAUNCH_JOURNEY = 'launch';
 
 const TAG_PATTERN = /<(script|link)\b([^>]*)>/gi;
+const HTML_COMMENT = /<!--[\s\S]*?-->/g;
+const INLINE_ELEMENT_BODY = /(<(script|style)\b[^>]*>)[\s\S]*?(<\/\2\s*>)/gi;
 const ATTRIBUTE_PATTERN =
     /([a-zA-Z_:][-a-zA-Z0-9_:.]*)(?:\s*=\s*(?:"([^"]*)"|'([^']*)'|([^\s"'=<>`]+)))?/g;
 const EXTERNAL_URL = /^(?:[a-z][a-z0-9+.-]*:|\/\/)/i;
@@ -56,6 +58,17 @@ function classify(tag, attributes) {
     return null;
 }
 
+/**
+ * Removes the parts of the document the browser never treats as markup: HTML
+ * comments (a commented-out `<script>` is not a request) and the bodies of
+ * inline `<script>`/`<style>` elements (a string literal that looks like a tag
+ * is not one either). The opening tags themselves are kept so a `src` on an
+ * inline script element is still seen.
+ */
+export function stripInertHtml(html) {
+    return html.replace(HTML_COMMENT, '').replace(INLINE_ELEMENT_BODY, '$1$3');
+}
+
 /**
  * Lists the same-origin resources `index.html` puts on the initial path, in
  * document order. Duplicates are collapsed by request URL, not by file: the
@@ -66,7 +79,9 @@ function classify(tag, attributes) {
 export function extractInitialResources(html) {
     const seen = new Set();
     const resources = [];
-    for (const [, tag, rawAttributes] of html.matchAll(TAG_PATTERN)) {
+    for (const [, tag, rawAttributes] of stripInertHtml(html).matchAll(
+        TAG_PATTERN
+    )) {
         const resource = classify(
             tag.toLowerCase(),
             parseAttributes(rawAttributes)
diff --git a/tools/performance/measure-initial-bytes.test.mjs b/tools/performance/measure-initial-bytes.test.mjs
index 35dd70d83..6ba1b9e56 100644
--- a/tools/performance/measure-initial-bytes.test.mjs
+++ b/tools/performance/measure-initial-bytes.test.mjs
@@ -13,6 +13,7 @@ import {
     formatReport,
     measureInitialBytes,
     parseArgs,
+    stripInertHtml,
     toJourneySummary,
 } from './measure-initial-bytes.mjs';
 
@@ -117,6 +118,23 @@ test('deduplicates by request URL, ignores fragments and normalizes relative URL
     ]);
 });
 
+test('ignores commented-out tags and tag-like text inside inline scripts and styles', () => {
+    const html = `
+        <!-- <script src="old.js"></script> -->
+        <!--
+            <link rel="stylesheet" href="legacy.css">
+        -->
+        <script>const markup = '<script src="fake.js"><\\/script><link rel="modulepreload" href="fake-chunk.js">';</script>
+        <style>/* <link rel="stylesheet" href="fake.css"> */ body { color: red; }</style>
+        <script src="assets/app-config.js" defer></script>
+        <script src="main.js" type="module"></script>`;
+    assert.deepEqual(
+        extractInitialResources(html).map((resource) => resource.url),
+        ['assets/app-config.js', 'main.js']
+    );
+    assert.equal(stripInertHtml('<script>1 < 2</script>'), '<script></script>');
+});
+
 test('counts a file once per distinct request URL', async () => {
     const distDir = await writeDist('cache-busted', {
         indexHtml: `<link rel="modulepreload" href="chunk-a.js"><link rel="modulepreload" href="chunk-a.js?v=2">`,