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1<!doctype html><html lang=en dir=ltr class="docs-wrapper plugin-docs plugin-id-default docs-version-0.79 docs-doc-page docs-doc-id-performance" data-has-hydrated=false><meta charset=UTF-8><meta name=generator content="Docusaurus v3.8.0"><title data-rh=true>Performance Overview · React Native</title><meta data-rh=true name=viewport content="width=device-width, initial-scale=1.0"><meta data-rh=true property=og:url content=https://reactnative.dev/docs/performance><meta data-rh=true property=og:locale content=en><meta data-rh=true name=docusaurus_locale content=en><meta data-rh=true name=docsearch:language content=en><meta data-rh=true property=og:image content=https://reactnative.dev/img/logo-share.png><meta data-rh=true name=twitter:card content=summary_large_image><meta data-rh=true name=twitter:image content=https://reactnative.dev/img/logo-share.png><meta data-rh=true name=twitter:site content=@reactnative><meta data-rh=true name=docusaurus_version content=0.79><meta data-rh=true name=docusaurus_tag content=docs-default-0.79><meta data-rh=true name=docsearch:version content=0.79><meta data-rh=true name=docsearch:docusaurus_tag content=docs-default-0.79><meta data-rh=true property=og:title content="Performance Overview · React Native"><meta data-rh=true name=description content="A compelling reason to use React Native instead of WebView-based tools is to achieve at least 60 frames per second and provide a native look and feel to your apps. Whenever feasible, we aim for React Native to handle optimizations automatically, allowing you to focus on your app without worrying about performance. However, there are certain areas where we haven't quite reached that level yet, and others where React Native (similar to writing native code directly) cannot determine the best optimization approach for you. In such cases, manual intervention becomes necessary. We strive to deliver buttery-smooth UI performance by default, but there may be instances where that isn't possible."><meta data-rh=true property=og:description content="A compelling reason to use React Native instead of WebView-based tools is to achieve at least 60 frames per second and provide a native look and feel to your apps. Whenever feasible, we aim for React Native to handle optimizations automatically, allowing you to focus on your app without worrying about performance. However, there are certain areas where we haven't quite reached that level yet, and others where React Native (similar to writing native code directly) cannot determine the best optimization approach for you. In such cases, manual intervention becomes necessary. We strive to deliver buttery-smooth UI performance by default, but there may be instances where that isn't possible."><link data-rh=true rel=icon href=/img/favicon.ico><link data-rh=true rel=canonical href=https://reactnative.dev/docs/performance><link data-rh=true rel=alternate href=https://reactnative.dev/docs/performance hreflang=en><link data-rh=true rel=alternate href=https://reactnative.dev/docs/performance hreflang=x-default><link data-rh=true rel=preconnect href=https://8TDSE0OHGQ-dsn.algolia.net crossorigin=anonymous><link rel=alternate type=application/rss+xml href=/blog/rss.xml title="React Native RSS Feed"><link rel=alternate type=application/atom+xml href=/blog/atom.xml title="React Native Atom Feed"><link rel=alternate type=application/json href=/blog/feed.json title="React Native JSON Feed"><link rel=preconnect href=https://www.google-analytics.com><script>window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)},ga.l=+new Date,ga("create","UA-41298772-2","auto"),ga("send","pageview")</script><script async src=https://www.google-analytics.com/analytics.js></script><link rel=preconnect href=https://www.google-analytics.com><link rel=preconnect href=https://www.googletagmanager.com><script async src="https://www.googletagmanager.com/gtag/js?id=G-58L13S6BDP"></script><script>function gtag(){dataLayer.push(arguments)}window.dataLayer=window.dataLayer||[],gtag("js",new Date),gtag("config","G-58L13S6BDP",{})</script><link rel=search type=application/opensearchdescription+xml title="React Native" href=/opensearch.xml><link rel=icon href=/img/pwa/manifest-icon-512.png><link rel=manifest href=/manifest.json><meta name=theme-color content=#20232a><meta name=apple-mobile-web-app-capable content=yes><meta name=apple-mobile-web-app-status-bar-style content=#20232a><link rel=apple-touch-icon href=/img/pwa/manifest-icon-512.png><link rel=mask-icon href=/img/pwa/manifest-icon-512.png color=#06bcee><meta name=msapplication-TileImage href=/img/pwa/manifest-icon-512.png><meta name=msapplication-TileColor content=#20232a><script src=https://cdn.jsdelivr.net/npm/focus-visible@5.2.0/dist/focus-visible.min.js defer></script><script src=https://widget.surveymonkey.com/collect/website/js/tRaiETqnLgj758hTBazgd8ryO5qrZo8Exadq9qmt1wtm4_2FdZGEAKHDFEt_2BBlwwM4.js defer></script><script src=https://snack.expo.dev/embed.js defer></script><script src=https://platform.twitter.com/widgets.js async></script><link rel=stylesheet href=/assets/css/styles.883cb042.css><script src=/assets/js/runtime~main.8ac1e6f0.js defer></script><script src=/assets/js/main.341783f5.js defer></script><body class=navigation-with-keyboard><svg xmlns=http://www.w3.org/2000/svg style="display: none;"><defs>
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Development</a></div><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class=menu__list-item-collapsible><a class="menu__link menu__link--sublist menu__link--sublist-caret" role=button aria-expanded=false href=/docs/headless-js-android>Android and iOS guides</a></div><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class=menu__list-item-collapsible><a class="menu__link menu__link--sublist menu__link--sublist-caret" role=button aria-expanded=false href=/docs/legacy/native-modules-intro>Legacy Architecture</a></div></ul></nav></div></div></aside><main class=docMainContainer_a9sJ><div class="container padding-top--md padding-bottom--lg"><div class=row><div class="col docItemCol_Qr34"><div class=docItemContainer_tjFy><article><div class="tocCollapsible_wXna theme-doc-toc-mobile tocMobile_Ojys"><button type=button class="clean-btn tocCollapsibleButton_iI2p">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>Performance Overview</h1></header><p>A compelling reason to use React Native instead of WebView-based tools is to achieve at least 60 frames per second and provide a native look and feel to your apps. Whenever feasible, we aim for React Native to handle optimizations automatically, allowing you to focus on your app without worrying about performance. However, there are certain areas where we haven't quite reached that level yet, and others where React Native (similar to writing native code directly) cannot determine the best optimization approach for you. In such cases, manual intervention becomes necessary. We strive to deliver buttery-smooth UI performance by default, but there may be instances where that isn't possible.</p>
5<p>This guide is intended to teach you some basics to help you to <a href=/docs/profiling>troubleshoot performance issues</a>, as well as discuss <a href=/docs/performance#common-sources-of-performance-problems>common sources of problems and their suggested solutions</a>.</p>
6<h2 class="anchor anchorWithStickyNavbar_JmGV" id=what-you-need-to-know-about-frames>What you need to know about frames<a href=#what-you-need-to-know-about-frames class=hash-link aria-label="Direct link to What you need to know about frames" title="Direct link to What you need to know about frames"></a></h2>
7<p>Your grandparents' generation called movies <a href="https://www.youtube.com/watch?v=F1i40rnpOsA" target=_blank rel="noopener noreferrer">"moving pictures"</a> for a reason: realistic motion in video is an illusion created by quickly changing static images at a consistent speed. We refer to each of these images as frames. The number of frames that is displayed each second has a direct impact on how smooth and ultimately life-like a video (or user interface) seems to be. iOS devices display at least 60 frames per second, which gives you and the UI system at most 16.67ms to do all of the work needed to generate the static image (frame) that the user will see on the screen for that interval. If you are unable to do the work necessary to generate that frame within the allotted time slot, then you will "drop a frame" and the UI will appear unresponsive.</p>
8<p>Now to confuse the matter a little bit, open up the <a href=/docs/debugging#opening-the-dev-menu>Dev Menu</a> in your app and toggle <code>Show Perf Monitor</code>. You will notice that there are two different frame rates.</p>
9<p><img decoding=async loading=lazy src=/assets/images/PerfUtil-38a2ddbf1777887d70563a644c72aa64.png width=522 height=138 class=img_SS3x></p>
10<h3 class="anchor anchorWithStickyNavbar_JmGV" id=js-frame-rate-javascript-thread>JS frame rate (JavaScript thread)<a href=#js-frame-rate-javascript-thread class=hash-link aria-label="Direct link to JS frame rate (JavaScript thread)" title="Direct link to JS frame rate (JavaScript thread)"></a></h3>
11<p>For most React Native applications, your business logic will run on the JavaScript thread. This is where your React application lives, API calls are made, touch events are processed, etc... Updates to native-backed views are batched and sent over to the native side at the end of each iteration of the event loop, before the frame deadline (if all goes well). If the JavaScript thread is unresponsive for a frame, it will be considered a dropped frame. For example, if you were to call <code>this.setState</code> on the root component of a complex application and it resulted in re-rendering computationally expensive component subtrees, it's conceivable that this might take 200ms and result in 12 frames being dropped. Any animations controlled by JavaScript would appear to freeze during that time. If anything takes longer than 100ms, the user will feel it.</p>
12<p>This often happens during <code>Navigator</code> transitions: when you push a new route, the JavaScript thread needs to render all of the components necessary for the scene in order to send over the proper commands to the native side to create the backing views. It's common for the work being done here to take a few frames and cause <a href=https://jankfree.org/ target=_blank rel="noopener noreferrer">jank</a> because the transition is controlled by the JavaScript thread. Sometimes components will do additional work on <code>componentDidMount</code>, which might result in a second stutter in the transition.</p>
13<p>Another example is responding to touches: if you are doing work across multiple frames on the JavaScript thread, you might notice a delay in responding to <code>TouchableOpacity</code>, for example. This is because the JavaScript thread is busy and cannot process the raw touch events sent over from the main thread. As a result, <code>TouchableOpacity</code> cannot react to the touch events and command the native view to adjust its opacity.</p>
14<h3 class="anchor anchorWithStickyNavbar_JmGV" id=ui-frame-rate-main-thread>UI frame rate (main thread)<a href=#ui-frame-rate-main-thread class=hash-link aria-label="Direct link to UI frame rate (main thread)" title="Direct link to UI frame rate (main thread)"></a></h3>
15<p>Many people have noticed that performance of <code>NavigatorIOS</code> is better out of the box than <code>Navigator</code>. The reason for this is that the animations for the transitions are done entirely on the main thread, and so they are not interrupted by frame drops on the JavaScript thread.</p>
16<p>Similarly, you can happily scroll up and down through a <code>ScrollView</code> when the JavaScript thread is locked up because the <code>ScrollView</code> lives on the main thread. The scroll events are dispatched to the JS thread, but their receipt is not necessary for the scroll to occur.</p>
17<h2 class="anchor anchorWithStickyNavbar_JmGV" id=common-sources-of-performance-problems>Common sources of performance problems<a href=#common-sources-of-performance-problems class=hash-link aria-label="Direct link to Common sources of performance problems" title="Direct link to Common sources of performance problems"></a></h2>
18<h3 class="anchor anchorWithStickyNavbar_JmGV" id=running-in-development-mode-devtrue>Running in development mode (<code>dev=true</code>)<a href=#running-in-development-mode-devtrue class=hash-link aria-label="Direct link to running-in-development-mode-devtrue" title="Direct link to running-in-development-mode-devtrue"></a></h3>
19<p>JavaScript thread performance suffers greatly when running in dev mode. This is unavoidable: a lot more work needs to be done at runtime to provide you with good warnings and error messages. Always make sure to test performance in <a href=/docs/running-on-device#building-your-app-for-production>release builds</a>.</p>
20<h3 class="anchor anchorWithStickyNavbar_JmGV" id=using-consolelog-statements>Using <code>console.log</code> statements<a href=#using-consolelog-statements class=hash-link aria-label="Direct link to using-consolelog-statements" title="Direct link to using-consolelog-statements"></a></h3>
21<p>When running a bundled app, these statements can cause a big bottleneck in the JavaScript thread. This includes calls from debugging libraries such as <a href=https://github.com/evgenyrodionov/redux-logger target=_blank rel="noopener noreferrer">redux-logger</a>, so make sure to remove them before bundling. You can also use this <a href=https://babeljs.io/docs/plugins/transform-remove-console/ target=_blank rel="noopener noreferrer">babel plugin</a> that removes all the <code>console.*</code> calls. You need to install it first with <code>npm i babel-plugin-transform-remove-console --save-dev</code>, and then edit the <code>.babelrc</code> file under your project directory like this:</p>
22<div class="language-json codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockTitle_kY6l>json</div><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-json codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"env"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"production"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token property" style=color:#2aa198>"plugins"</span><span class="token operator" style=color:#fc929e>:</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>[</span><span class="token string" style=color:#8dc891>"transform-remove-console"</span><span class="token punctuation" style=color:#657b83>]</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"></span><span class="token punctuation" style=color:#657b83>}</span><br></span></code></pre></div></div>
23<p>This will automatically remove all <code>console.*</code> calls in the release (production) versions of your project.</p>
24<p>It is recommended to use the plugin even if no <code>console.*</code> calls are made in your project. A third party library could also call them.</p>
25<h3 class="anchor anchorWithStickyNavbar_JmGV" id=listview-initial-rendering-is-too-slow-or-scroll-performance-is-bad-for-large-lists><code>ListView</code> initial rendering is too slow or scroll performance is bad for large lists<a href=#listview-initial-rendering-is-too-slow-or-scroll-performance-is-bad-for-large-lists class=hash-link aria-label="Direct link to listview-initial-rendering-is-too-slow-or-scroll-performance-is-bad-for-large-lists" title="Direct link to listview-initial-rendering-is-too-slow-or-scroll-performance-is-bad-for-large-lists"></a></h3>
26<p>Use the new <a href=/docs/flatlist><code>FlatList</code></a> or <a href=/docs/sectionlist><code>SectionList</code></a> component instead. Besides simplifying the API, the new list components also have significant performance enhancements, the main one being nearly constant memory usage for any number of rows.</p>
27<p>If your <a href=/docs/flatlist><code>FlatList</code></a> is rendering slow, be sure that you've implemented <a href=/docs/flatlist#getitemlayout><code>getItemLayout</code></a> to optimize rendering speed by skipping measurement of the rendered items.</p>
28<h3 class="anchor anchorWithStickyNavbar_JmGV" id=js-fps-plunges-when-re-rendering-a-view-that-hardly-changes>JS FPS plunges when re-rendering a view that hardly changes<a href=#js-fps-plunges-when-re-rendering-a-view-that-hardly-changes class=hash-link aria-label="Direct link to JS FPS plunges when re-rendering a view that hardly changes" title="Direct link to JS FPS plunges when re-rendering a view that hardly changes"></a></h3>
29<p>If you are using a ListView, you must provide a <code>rowHasChanged</code> function that can reduce a lot of work by quickly determining whether or not a row needs to be re-rendered. If you are using immutable data structures, this would only need to be a reference equality check.</p>
30<p>Similarly, you can implement <code>shouldComponentUpdate</code> and indicate the exact conditions under which you would like the component to re-render. If you write pure components (where the return value of the render function is entirely dependent on props and state), you can leverage PureComponent to do this for you. Once again, immutable data structures are useful to keep this fast -- if you have to do a deep comparison of a large list of objects, it may be that re-rendering your entire component would be quicker, and it would certainly require less code.</p>
31<h3 class="anchor anchorWithStickyNavbar_JmGV" id=dropping-js-thread-fps-because-of-doing-a-lot-of-work-on-the-javascript-thread-at-the-same-time>Dropping JS thread FPS because of doing a lot of work on the JavaScript thread at the same time<a href=#dropping-js-thread-fps-because-of-doing-a-lot-of-work-on-the-javascript-thread-at-the-same-time class=hash-link aria-label="Direct link to Dropping JS thread FPS because of doing a lot of work on the JavaScript thread at the same time" title="Direct link to Dropping JS thread FPS because of doing a lot of work on the JavaScript thread at the same time"></a></h3>
32<p>"Slow Navigator transitions" is the most common manifestation of this, but there are other times this can happen. Using InteractionManager can be a good approach, but if the user experience cost is too high to delay work during an animation, then you might want to consider LayoutAnimation.</p>
33<p>The Animated API currently calculates each keyframe on-demand on the JavaScript thread unless you <a href=/blog/2017/02/14/using-native-driver-for-animated#how-do-i-use-this-in-my-app>set <code>useNativeDriver: true</code></a>, while LayoutAnimation leverages Core Animation and is unaffected by JS thread and main thread frame drops.</p>
34<p>One case where I have used this is for animating in a modal (sliding down from top and fading in a translucent overlay) while initializing and perhaps receiving responses for several network requests, rendering the contents of the modal, and updating the view where the modal was opened from. See the Animations guide for more information about how to use LayoutAnimation.</p>
35<p>Caveats:</p>
36<ul>
37<li>LayoutAnimation only works for fire-and-forget animations ("static" animations) -- if it must be interruptible, you will need to use <code>Animated</code>.</li>
38</ul>
39<h3 class="anchor anchorWithStickyNavbar_JmGV" id=moving-a-view-on-the-screen-scrolling-translating-rotating-drops-ui-thread-fps>Moving a view on the screen (scrolling, translating, rotating) drops UI thread FPS<a href=#moving-a-view-on-the-screen-scrolling-translating-rotating-drops-ui-thread-fps class=hash-link aria-label="Direct link to Moving a view on the screen (scrolling, translating, rotating) drops UI thread FPS" title="Direct link to Moving a view on the screen (scrolling, translating, rotating) drops UI thread FPS"></a></h3>
40<p>This is especially true when you have text with a transparent background positioned on top of an image, or any other situation where alpha compositing would be required to re-draw the view on each frame. You will find that enabling <code>shouldRasterizeIOS</code> or <code>renderToHardwareTextureAndroid</code> can help with this significantly.</p>
41<p>Be careful not to overuse this or your memory usage could go through the roof. Profile your performance and memory usage when using these props. If you don't plan to move a view anymore, turn this property off.</p>
42<h3 class="anchor anchorWithStickyNavbar_JmGV" id=animating-the-size-of-an-image-drops-ui-thread-fps>Animating the size of an image drops UI thread FPS<a href=#animating-the-size-of-an-image-drops-ui-thread-fps class=hash-link aria-label="Direct link to Animating the size of an image drops UI thread FPS" title="Direct link to Animating the size of an image drops UI thread FPS"></a></h3>
43<p>On iOS, each time you adjust the width or height of an Image component it is re-cropped and scaled from the original image. This can be very expensive, especially for large images. Instead, use the <code>transform: [{scale}]</code> style property to animate the size. An example of when you might do this is when you tap an image and zoom it in to full screen.</p>
44<h3 class="anchor anchorWithStickyNavbar_JmGV" id=my-touchablex-view-isnt-very-responsive>My TouchableX view isn't very responsive<a href=#my-touchablex-view-isnt-very-responsive class=hash-link aria-label="Direct link to My TouchableX view isn't very responsive" title="Direct link to My TouchableX view isn't very responsive"></a></h3>
45<p>Sometimes, if we do an action in the same frame that we are adjusting the opacity or highlight of a component that is responding to a touch, we won't see that effect until after the <code>onPress</code> function has returned. If <code>onPress</code> does a <code>setState</code> that results in a lot of work and a few frames dropped, this may occur. A solution to this is to wrap any action inside of your <code>onPress</code> handler in <code>requestAnimationFrame</code>:</p>
46<div class="language-tsx codeBlockContainer_mQmQ theme-code-block" style=--prism-color:#FFFFFF;--prism-background-color:#282C34><div class=codeBlockTitle_kY6l>tsx</div><div class=codeBlockContent_t_Hd><pre tabindex=0 class="prism-code language-tsx codeBlock_RMoD thin-scrollbar" style=color:#FFFFFF;background-color:#282C34><code class=codeBlockLines_AclH><span class=token-line style=color:#FFFFFF><span class="token function" style=color:#79b6f2>handleOnPress</span><span class="token punctuation" style=color:#657b83>(</span><span class="token punctuation" style=color:#657b83>)</span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token function" style=color:#79b6f2>requestAnimationFrame</span><span class="token punctuation" style=color:#657b83>(</span><span class="token punctuation" style=color:#657b83>(</span><span class="token punctuation" style=color:#657b83>)</span><span class="token plain"> </span><span class="token arrow operator" style=color:#fc929e>=></span><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>{</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token keyword" style=color:#c5a5c5>this</span><span class="token punctuation" style=color:#657b83>.</span><span class="token method function property-access" style=color:#79b6f2>doExpensiveAction</span><span class="token punctuation" style=color:#657b83>(</span><span class="token punctuation" style=color:#657b83>)</span><span class="token punctuation" style=color:#657b83>;</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"> </span><span class="token punctuation" style=color:#657b83>}</span><span class="token punctuation" style=color:#657b83>)</span><span class="token punctuation" style=color:#657b83>;</span><span class="token plain"></span><br></span><span class=token-line style=color:#FFFFFF><span class="token plain"></span><span class="token punctuation" style=color:#657b83>}</span><br></span></code></pre></div></div>
47<h3 class="anchor anchorWithStickyNavbar_JmGV" id=slow-navigator-transitions>Slow navigator transitions<a href=#slow-navigator-transitions class=hash-link aria-label="Direct link to Slow navigator transitions" title="Direct link to Slow navigator transitions"></a></h3>
48<p>As mentioned above, <code>Navigator</code> animations are controlled by the JavaScript thread. Imagine the "push from right" scene transition: each frame, the new scene is moved from the right to left, starting offscreen (let's say at an x-offset of 320) and ultimately settling when the scene sits at an x-offset of 0. Each frame during this transition, the JavaScript thread needs to send a new x-offset to the main thread. If the JavaScript thread is locked up, it cannot do this and so no update occurs on that frame and the animation stutters.</p>
49<p>One solution to this is to allow for JavaScript-based animations to be offloaded to the main thread. If we were to do the same thing as in the above example with this approach, we might calculate a list of all x-offsets for the new scene when we are starting the transition and send them to the main thread to execute in an optimized way. Now that the JavaScript thread is freed of this responsibility, it's not a big deal if it drops a few frames while rendering the scene -- you probably won't even notice because you will be too distracted by the pretty transition.</p>
50<p>Solving this is one of the main goals behind the new <a href=/docs/navigation>React Navigation</a> library. 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