[[["易于理解","easyToUnderstand","thumb-up"],["解决了我的问题","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["没有我需要的信息","missingTheInformationINeed","thumb-down"],["太复杂/步骤太多","tooComplicatedTooManySteps","thumb-down"],["内容需要更新","outOfDate","thumb-down"],["翻译问题","translationIssue","thumb-down"],["示例/代码问题","samplesCodeIssue","thumb-down"],["其他","otherDown","thumb-down"]],["最后更新时间 (UTC)：2025-07-25。"],[[["\u003cp\u003ePageSpeed Insights (PSI) assesses the performance of web pages on both mobile and desktop, offering suggestions for optimization by analyzing lab and real-world data.\u003c/p\u003e\n"],["\u003cp\u003ePSI utilizes the Chrome User Experience Report (CrUX) for real-world data, measuring metrics like First Contentful Paint (FCP), Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP).\u003c/p\u003e\n"],["\u003cp\u003eLab data is generated through Lighthouse, simulating page load and providing diagnostics on performance, accessibility, best practices, and SEO.\u003c/p\u003e\n"],["\u003cp\u003ePSI categorizes user experiences into Good, Needs Improvement, and Poor based on established thresholds for key performance metrics.\u003c/p\u003e\n"],["\u003cp\u003eCore Web Vitals, a subset of critical performance signals, includes LCP, CLS, and INP, and their assessment determines the overall page experience quality.\u003c/p\u003e\n"]]],["PageSpeed Insights (PSI) analyzes page performance on mobile and desktop, offering lab and field data. Field data, powered by the Chrome User Experience Report (CrUX), reflects real-world user experiences, measuring metrics like First Contentful Paint (FCP), Interaction to Next Paint (INP), Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Time to First Byte (TTFB), and the quality of them. PSI classifies experiences as Good, Needs Improvement, or Poor. Lab data uses Lighthouse to simulate page loads, providing diagnostic scores and metrics.\n"],null,["PageSpeed Insights (PSI) reports on the user experience of a page on both mobile and desktop\ndevices, and provides suggestions on how that page may be improved.\n\n\nPSI provides both lab and field data about a page. Lab data is useful for debugging\nissues, as it is collected in a controlled environment. However, it may not\ncapture real-world bottlenecks. Field data is useful for capturing true, real-world user\nexperience - but has a more limited set of metrics. See [How To Think\nAbout Speed Tools](/web/fundamentals/performance/speed-tools) for more information on the two types of data.\n\nReal-user experience data\n\n\nReal-user experience data in PSI is powered by the [Chrome User Experience\nReport](/web/tools/chrome-user-experience-report) (CrUX) dataset. PSI reports real users' [First\nContentful Paint](https://web.dev/articles/fcp) (FCP), [Interaction to Next Paint](https://web.dev/articles/inp) (INP),\n[Largest Contentful Paint](https://web.dev/articles/lcp) (LCP), and [Cumulative Layout\nShift](https://web.dev/articles/cls) (CLS) experiences over the previous 28-day collection period. PSI also reports\nexperiences for the experimental metric [Time to First Byte](https://web.dev/articles/ttfb) (TTFB).\n\n\nIn order to show user experience data for a given page, there must be sufficient data for it\nto be included in the CrUX dataset. A page might not have sufficient data if it has been\nrecently published or has too few samples from real users. When this happens, PSI will fall\nback to origin-level granularity, which encompasses all user experiences on all pages of the\nwebsite. Sometimes the origin may also have insufficient data, in which case PSI will be\nunable to show any real-user experience data.\n\nAssessing quality of experiences\n\n\nPSI classifies the quality of user experiences into three buckets: Good, Needs Improvement,\nor Poor. PSI sets the following thresholds in alignment with the\n[Web Vitals](https://web.dev/articles/vitals) initiative:\n\n| | Good | Needs Improvement | Poor |\n|---------------------|---------------|-------------------|-------------|\n| FCP | \\[0, 1800ms\\] | (1800ms, 3000ms\\] | over 3000ms |\n| LCP | \\[0, 2500ms\\] | (2500ms, 4000ms\\] | over 4000ms |\n| CLS | \\[0, 0.1\\] | (0.1, 0.25\\] | over 0.25 |\n| INP | \\[0, 200ms\\] | (200ms, 500ms\\] | over 500ms |\n| TTFB (experimental) | \\[0, 800ms\\] | (800ms, 1800ms\\] | over 1800ms |\n\nDistribution and selected metric values\n\n\nPSI presents a distribution of these metrics so that developers can understand the range of\nexperiences for that page or origin. This distribution is split into three categories:\nGood, Needs Improvement, and Poor, which are represented by green, amber, and red bars.\nFor example, seeing 11% within LCP's amber bar indicates that 11% of all observed LCP values\nfall between 2500ms and 4000ms.\n\n\nAbove the distribution bars, PSI reports the 75th percentile for all metrics. The 75th\npercentile is [selected](#why-is-the-75th-percentile-chosen-for-all-metrics) so that developers can understand the most\nfrustrating user experiences on their site. These field metric values are classified as\ngood/needs improvement/poor by applying the same thresholds shown above.\n\nCore Web Vitals\n\n\nCore Web Vitals are a common set of performance signals critical to\nall web experiences. The Core Web Vitals metrics are INP, LCP, and CLS, and they may be\naggregated at either the page or origin level. For aggregations with sufficient data in all\nthree metrics, the aggregation passes the Core Web Vitals assessment if the 75th percentiles\nof all three metrics are Good. Otherwise, the aggregation does not pass the assessment. If the\naggregation has insufficient data for INP, then it will pass the assessment if both the 75th\npercentiles of LCP and CLS are Good. If either LCP or CLS have insufficient data, the page or\norigin-level aggregation cannot be assessed.\n\nDifferences between Field Data in PSI and CrUX\n\n\nThe difference between the field data in PSI versus the\n[CrUX dataset on BigQuery](https://developer.chrome.com/docs/crux/guides/bigquery) is that PSI's data is updated daily,\nwhile the BigQuery dataset is updated monthly and limited to origin-level data.\nBoth data sources represent trailing 28-day periods.\n\nLab diagnostics\n\n\nPSI uses [Lighthouse](https://developer.chrome.com/docs/lighthouse/) to analyze the given URL in a simulated\nenvironment for the Performance, Accessibility, Best Practices, and SEO categories.\n\nScore\n\n\nAt the top of the section are scores for each category, determined by running Lighthouse\nto collect and analyze diagnostic information about the page. A score of 90 or above is\nconsidered good. 50 to 89 is a score that needs improvement, and below 50 is considered poor.\n\nMetrics\n\n\nThe Performance category also has the page's performance on different metrics, including:\n[First Contentful Paint](https://web.dev/articles/fcp),\n[Largest Contentful Paint](https://web.dev/articles/lcp),\n[Speed Index](https://developer.chrome.com/docs/lighthouse/performance/speed-index/),\n[Cumulative Layout Shift](https://web.dev/articles/cls),\n[Time to Interactive](https://developer.chrome.com/docs/lighthouse/performance/interactive/),\nand [Total Blocking Time](https://web.dev/articles/tbt).\n\nEach metric is [scored](https://developer.chrome.com/docs/lighthouse/performance/performance-scoring/) and labeled with a icon:\n\n- Good is indicated with a green circle\n- Needs Improvement is indicated with amber informational square\n- Poor is indicated with a red warning triangle\n\nAudits\n\n\nWithin each category are audits that provide information on how to improve the page's user\nexperience. See the [Lighthouse documentation](https://developer.chrome.com/docs/lighthouse/) for a detailed\nbreakdown of each category's audits.\n\nFrequently asked questions (FAQs)\n\nWhat device and network conditions does Lighthouse use to simulate a page load?\n\n\nCurrently, Lighthouse simulates the page load conditions of a mid-tier device (Moto G4) device\non a [mobile network](https://github.com/GoogleChrome/lighthouse/blob/master/docs/throttling.md) for mobile, and an\nemulated-desktop with a wired connection for desktop. PageSpeed also runs in a Google\ndatacenter that can vary based on network conditions, you can check the location that the test\nwas by looking at the Lighthouse Report's environment block:\n\n\nNote: PageSpeed will report running in one of: North America, Europe, or Asia.\n\nWhy do the field data and lab data sometimes contradict each other?\n\n\nThe field data is a historical report about how a particular URL has performed, and represents\nanonymized performance data from users in the real-world on a variety of devices and network\nconditions. The lab data is based on a simulated load of a page on a single device and fixed\nset of network conditions. As a result, the values may differ.\nSee [Why lab and field data can be different\n(and what to do about it)](https://web.dev/articles/lab-and-field-data-differences) for more info.\n\nWhy is the 75th percentile chosen for all metrics?\n\n\nOur goal is to make sure that pages work well for the majority of users. By focusing on 75th\npercentile values for our metrics, this ensures that pages provide a good user experience\nunder the most difficult device and network conditions.\nSee [Defining the Core Web Vitals metrics thresholds](https://web.dev/articles/defining-core-web-vitals-thresholds)\nfor more info.\n\nWhat is a good score for the lab data?\n\n\nAny green score (90+) is considered good, but note that having good lab data does not\nnecessarily mean real-user experiences will also be good.\n\nWhy does the performance score change from run to run? I didn't change anything on my page!\n\n\n[Variability](https://developer.chrome.com/docs/lighthouse/performance/performance-scoring/#fluctuations) in performance measurement is introduced via a\nnumber of channels with different levels of impact. Several common sources of metric\nvariability are local network availability, client hardware availability, and client resource\ncontention.\n\nWhy is the real-user CrUX data not available for a URL or origin?\n\n\nChrome User Experience Report aggregates real-world speed data from\n[opted-in users](https://developer.chrome.com/docs/crux/methodology) and\nrequires that a URL must be public\n([crawlable and indexable](https://developer.chrome.com/docs/lighthouse/seo/is-crawlable/))\nand have sufficient number of distinct samples that provide a representative, anonymized view\nof performance of the URL or origin.\n\nMore questions?\n\n\nIf you've got a question about using PageSpeed Insights that is specific and answerable,\nask your question in English on [Stack Overflow](https://stackoverflow.com/questions/tagged/pagespeed-insights).\n\n\nIf you have general feedback or questions about PageSpeed Insights, or you want to start a\ngeneral discussion, start a thread in the [mailing list](https://groups.google.com/forum/#!forum/pagespeed-insights-discuss).\n\n\nIf you have general questions about the Web Vitals metrics, start a thread in the [web-vitals-feedback](https://groups.google.com/g/web-vitals-feedback) discussion group.\n\nFeedback\n\nWas this page helpful? \nYes Great! Thank you for the feedback. If you have a specific, answerable question about using PageSpeed Insights, ask the question in English on [Stack\n| Overflow](https://stackoverflow.com/questions/tagged/pagespeed-insights). For general questions, feedback, and discussion, start a thread in the [mailing list](https://groups.google.com/forum/#!forum/pagespeed-insights-discuss).\nNo Sorry to hear that. If you have a specific, answerable question about using PageSpeed Insights, ask the question in English on [Stack\n| Overflow](https://stackoverflow.com/questions/tagged/pagespeed-insights). For general questions, feedback, and discussion, start a thread in the [mailing list](https://groups.google.com/forum/#!forum/pagespeed-insights-discuss)."]]
