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Add Performance Issues to Perf Monitor (1/2) - #54265

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Add Performance Issues to Perf Monitor (1/2)#54265
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@huntiehuntie commented Oct 24, 2025•
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Summary:
Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.

Design

Performance Issues are an experimental user space API via the User Timings detail object.

performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});

When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.

This diff

This feature is gated by the perfMonitorV2Enabled feature flag.

Changelog: [Internal]

Differential Revision: D85448200

@meta-clameta-claBot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Oct 24, 2025
@huntiehuntie mentioned this pull request Oct 28, 2025
Merged
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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.

@huntie@facebook-github-bot
Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-codesync

meta-codesyncBot commented Oct 31, 2025

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This pull request has been merged in ee9ef3b.

@facebook-github-botfacebook-github-bot added the Merged This PR has been merged. label Oct 31, 2025
@react-native-bot

react-native-bot commented Oct 31, 2025

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This pull request was successfully merged by @huntie in ee9ef3b

When will my fix make it into a release? | How to file a pick request?

@huntie
huntie deleted the export-D85448200 branch October 31, 2025 17:38
@huntiehuntie mentioned this pull request Nov 3, 2025
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, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
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(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Add Performance Issues to Perf Monitor (1/2) by huntie · Pull Request #54265 · react/react-native · GitHub
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Add Performance Issues to Perf Monitor (1/2) - #54265
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huntie wants to merge 1 commit into
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huntie:export-D85448200
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Add Performance Issues to Perf Monitor (1/2)#54265
huntie wants to merge 1 commit into
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huntie:export-D85448200
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@huntie
@huntiehuntie
commented
Oct 24, 2025•

edited

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Collaborator
Summary:

Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.
Design
Performance Issues are an experimental user space API via the User Timings detail object.
performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});
When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.
This diff
This feature is gated by the perfMonitorV2Enabled feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-clameta-claBot
added
the 
CLA Signed
This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed.
label
Oct 24, 2025
@huntiehuntie
mentioned this pull request
Oct 28, 2025
 Merged

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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.
@huntie@facebook-github-bot
Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-codesync
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Oct 31, 2025

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This pull request has been merged in ee9ef3b.
@facebook-github-botfacebook-github-bot
added
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This pull request was successfully merged by @huntie in ee9ef3b
When will my fix make it into a release? | How to file a pick request?
@huntie
huntie
deleted the

export-D85448200

branch
October 31, 2025 17:38
@huntiehuntie
mentioned this pull request
Nov 3, 2025
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Add Performance Issues to Perf Monitor (1/2) by huntie · Pull Request #54265 · react/react-native · GitHub
Skip to content
Add Performance Issues to Perf Monitor (1/2) - #54265
Closed
huntie wants to merge 1 commit into
react:mainfrom 
huntie:export-D85448200
Closed
Add Performance Issues to Perf Monitor (1/2)#54265
huntie wants to merge 1 commit into
react:mainfrom 
huntie:export-D85448200
Conversation
@huntie
@huntiehuntie
commented
Oct 24, 2025•

edited

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Collaborator
Summary:

Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.
Design
Performance Issues are an experimental user space API via the User Timings detail object.
performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});
When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.
This diff
This feature is gated by the perfMonitorV2Enabled feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-clameta-claBot
added
the 
CLA Signed
This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed.
label
Oct 24, 2025
@huntiehuntie
mentioned this pull request
Oct 28, 2025
 Merged

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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.
@huntie@facebook-github-bot
Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-codesync
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This pull request has been merged in ee9ef3b.
@facebook-github-botfacebook-github-bot
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This pull request was successfully merged by @huntie in ee9ef3b
When will my fix make it into a release? | How to file a pick request?
@huntie
huntie
deleted the

export-D85448200

branch
October 31, 2025 17:38
@huntiehuntie
mentioned this pull request
Nov 3, 2025
 Merged

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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
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var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
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var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
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Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
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mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Add Performance Issues to Perf Monitor (1/2) by huntie · Pull Request #54265 · react/react-native · GitHub
Skip to content
Add Performance Issues to Perf Monitor (1/2) - #54265
Closed
huntie wants to merge 1 commit into
react:mainfrom 
huntie:export-D85448200
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Add Performance Issues to Perf Monitor (1/2)#54265
huntie wants to merge 1 commit into
react:mainfrom 
huntie:export-D85448200
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@huntie
@huntiehuntie
commented
Oct 24, 2025•

edited

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Summary:

Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.
Design
Performance Issues are an experimental user space API via the User Timings detail object.
performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});
When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.
This diff
This feature is gated by the perfMonitorV2Enabled feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-clameta-claBot
added
the 
CLA Signed
This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed.
label
Oct 24, 2025
@huntiehuntie
mentioned this pull request
Oct 28, 2025
 Merged

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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.
@huntie@facebook-github-bot
Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
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This pull request has been merged in ee9ef3b.
@facebook-github-botfacebook-github-bot
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This pull request was successfully merged by @huntie in ee9ef3b
When will my fix make it into a release? | How to file a pick request?
@huntie
huntie
deleted the

export-D85448200

branch
October 31, 2025 17:38
@huntiehuntie
mentioned this pull request
Nov 3, 2025
 Merged

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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Add Performance Issues to Perf Monitor (1/2) by huntie · Pull Request #54265 · react/react-native · GitHub
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Add Performance Issues to Perf Monitor (1/2) - #54265
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huntie wants to merge 1 commit into
react:mainfrom 
huntie:export-D85448200
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Add Performance Issues to Perf Monitor (1/2)#54265
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Oct 24, 2025•

edited

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Summary:

Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.
Design
Performance Issues are an experimental user space API via the User Timings detail object.
performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});
When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.
This diff
This feature is gated by the perfMonitorV2Enabled feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-clameta-claBot
added
the 
CLA Signed
This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed.
label
Oct 24, 2025
@huntiehuntie
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Oct 28, 2025
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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.
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Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Add Performance Issues to Perf Monitor (1/2) by huntie · Pull Request #54265 · react/react-native · GitHub
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Add Performance Issues to Perf Monitor (1/2) - #54265
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Add Performance Issues to Perf Monitor (1/2)#54265
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Oct 24, 2025•

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Summary:

Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.
Design
Performance Issues are an experimental user space API via the User Timings detail object.
performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});
When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.
This diff
This feature is gated by the perfMonitorV2Enabled feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-clameta-claBot
added
the 
CLA Signed
This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed.
label
Oct 24, 2025
@huntiehuntie
mentioned this pull request
Oct 28, 2025
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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.
@huntie@facebook-github-bot
Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-codesync
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Oct 31, 2025

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This pull request has been merged in ee9ef3b.
@facebook-github-botfacebook-github-bot
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Oct 31, 2025
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This pull request was successfully merged by @huntie in ee9ef3b
When will my fix make it into a release? | How to file a pick request?
@huntie
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deleted the

export-D85448200

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October 31, 2025 17:38
@huntiehuntie
mentioned this pull request
Nov 3, 2025
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Add Performance Issues to Perf Monitor (1/2) by huntie · Pull Request #54265 · react/react-native · GitHub
Skip to content
Add Performance Issues to Perf Monitor (1/2) - #54265
Closed
huntie wants to merge 1 commit into
react:mainfrom 
huntie:export-D85448200
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Add Performance Issues to Perf Monitor (1/2)#54265
huntie wants to merge 1 commit into
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Oct 24, 2025•

edited

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Summary:

Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.
Design
Performance Issues are an experimental user space API via the User Timings detail object.
performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});
When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.
This diff
This feature is gated by the perfMonitorV2Enabled feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-clameta-claBot
added
the 
CLA Signed
This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed.
label
Oct 24, 2025
@huntiehuntie
mentioned this pull request
Oct 28, 2025
 Merged

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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.
@huntie@facebook-github-bot
Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-codesync
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Oct 31, 2025

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This pull request has been merged in ee9ef3b.
@facebook-github-botfacebook-github-bot
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This pull request was successfully merged by @huntie in ee9ef3b
When will my fix make it into a release? | How to file a pick request?
@huntie
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deleted the

export-D85448200

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October 31, 2025 17:38
@huntiehuntie
mentioned this pull request
Nov 3, 2025
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
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[data-theme="light"], [data-theme="light"],
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filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
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// Toggle with Alt+Shift+D
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e.preventDefault();
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applyDarkMode();
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console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
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})();
})();
Add Performance Issues to Perf Monitor (1/2) by huntie · Pull Request #54265 · react/react-native · GitHub
Skip to content
Add Performance Issues to Perf Monitor (1/2) - #54265
Closed
huntie wants to merge 1 commit into
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huntie:export-D85448200
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Add Performance Issues to Perf Monitor (1/2)#54265
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huntie:export-D85448200
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Oct 24, 2025•

edited

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Collaborator
Summary:

Introduces the concept of Performance Issues, an experimental performance signals concept for React Native.
Design
Performance Issues are an experimental user space API via the User Timings detail object.
performance.measure({
start,
end,detail: {devtools: {
...
},rnPerfIssue: {name: 'React: Cascading Update',severity: 'warning',// 'info' | 'warning' | 'error',description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',}}});
When rnPerfIssue is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the "__react_native_perf_issues_reporter" runtime binding.
This diff
This feature is gated by the perfMonitorV2Enabled feature flag.
Changelog: [Internal]
Differential Revision: D85448200
@meta-clameta-claBot
added
the 
CLA Signed
This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed.
label
Oct 24, 2025
@huntiehuntie
mentioned this pull request
Oct 28, 2025
 Merged

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@huntie has exported this pull request. If you are a Meta employee, you can view the originating Diff in D85448200.
@huntie@facebook-github-bot
Add Performance Issues to Perf Monitor (1/2) (#54265)
ecb9840
Summary:
Introduces the concept of **Performance Issues**, an experimental performance signals concept for React Native.
**Design**
Performance Issues are an **experimental** user space API via the User Timings `detail` object.
```
performance.measure({
start,
end,
detail: {
devtools: {
...
},
rnPerfIssue: {
name: 'React: Cascading Update',
severity: 'warning', // 'info' | 'warning' | 'error',
description:
'A cascading update is a update that is triggered by a previous update. This can lead to performance issues and should be avoided.',
learnMoreUrl:
'https://react.dev/reference/dev-tools/react-performance-tracks#cascading-updates',
}
}
});
```
When `rnPerfIssue` is present, we eagerly report an the event over CDP, regardless of an active performance trace, via the `"__react_native_perf_issues_reporter"` runtime binding.
**This diff**
- Adds a `perfIssuesEnabled` feature flag.
- Initial implementation of the above API.
- Initially reports a "Cascading Render" issue, aligning 1:1 with the corresponding React performance track event (note: to be added in the React codebase, see react/react#34961).
This feature is gated by the `perfMonitorV2Enabled` feature flag.
Changelog: [Internal]
Differential Revision: D85448200
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This pull request has been merged in ee9ef3b.
@facebook-github-botfacebook-github-bot
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This pull request was successfully merged by @huntie in ee9ef3b
When will my fix make it into a release? | How to file a pick request?
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October 31, 2025 17:38
@huntiehuntie
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