Chrome DevTools MCP で AI エージェントのフロントエンド開発をサポートする

⎿ # performance_start_trace response
    The performance trace has been stopped.
    Here is a high level summary of the trace and the Insights that were
    found:
    Information on performance traces may contain main thread activity
    represented as call frames and network requests.
 
    Each call frame is presented in the following format:
 
    'id;eventKey;name;duration;selfTime;urlIndex;childRange;[S]'
 
    Key definitions:
 
    * id: A unique numerical identifier for the call frame. Never mention
    this id in the output to the user.
    * eventKey: String that uniquely identifies this event in the flame
    chart.
    * name: A concise string describing the call frame (e.g., 'Evaluate
    Script', 'render', 'fetchData').
    * duration: The total execution time of the call frame, including its
    children.
    * selfTime: The time spent directly within the call frame, excluding
    its children's execution.
    * urlIndex: Index referencing the "All URLs" list. Empty if no
    specific script URL is associated.
    * childRange: Specifies the direct children of this node using their
    IDs. If empty ('' or 'S' at the end), the node has no children. If a
    single number (e.g., '4'), the node has one child with that ID. If in
    the format 'firstId-lastId' (e.g., '4-5'), it indicates a consecutive
    range of child IDs from 'firstId' to 'lastId', inclusive.
    * S: _Optional_. The letter 'S' terminates the line if that call frame
     was selected by the user.
 
    Example Call Tree:
 
    1;r-123;main;500;100;;
    2;r-124;update;200;50;;3
    3;p-49575-15428179-2834-374;animate;150;20;0;4-5;S
    4;p-49575-15428179-3505-1162;calculatePosition;80;80;;
    5;p-49575-15428179-5391-2767;applyStyles;50;50;;
 
 
    Network requests are formatted like this:
    `urlIndex;eventKey;queuedTime;requestSentTime;downloadCompleteTime;pro
    cessingCompleteTime;totalDuration;downloadDuration;mainThreadProcessin
    gDuration;statusCode;mimeType;priority;initialPriority;finalPriority;r
    enderBlocking;protocol;fromServiceWorker;initiators;redirects:[[redire
    ctUrlIndex|startTime|duration]];responseHeaders:[header1Value|header2V
    alue|...]`
 
    - `urlIndex`: Numerical index for the request's URL, referencing the
    "All URLs" list.
    - `eventKey`: String that uniquely identifies this request's trace
    event.
    Timings (all in milliseconds, relative to navigation start):
    - `queuedTime`: When the request was queued.
    - `requestSentTime`: When the request was sent.
    - `downloadCompleteTime`: When the download completed.
    - `processingCompleteTime`: When main thread processing finished.
    Durations (all in milliseconds):
    - `totalDuration`: Total time from the request being queued until its
    main thread processing completed.
    - `downloadDuration`: Time spent actively downloading the resource.
    - `mainThreadProcessingDuration`: Time spent on the main thread after
    the download completed.
    - `statusCode`: The HTTP status code of the response (e.g., 200, 404).
    - `mimeType`: The MIME type of the resource (e.g., "text/html",
    "application/javascript").
    - `priority`: The final network request priority (e.g., "VeryHigh",
    "Low").
    - `initialPriority`: The initial network request priority.
    - `finalPriority`: The final network request priority (redundant if
    `priority` is always final, but kept for clarity if `initialPriority`
    and `priority` differ).
    - `renderBlocking`: 't' if the request was render-blocking, 'f'
    otherwise.
    - `protocol`: The network protocol used (e.g., "h2", "http/1.1").
    - `fromServiceWorker`: 't' if the request was served from a service
    worker, 'f' otherwise.
    - `initiators`: A list (separated by ,) of URL indices for the
    initiator chain of this request. Listed in order starting from the
    root request to the request that directly loaded this one. This
    represents the network dependencies necessary to load this request. If
     there is no initiator, this is empty.
    - `redirects`: A comma-separated list of redirects, enclosed in square
     brackets. Each redirect is formatted as
    `[redirectUrlIndex|startTime|duration]`, where: `redirectUrlIndex`:
    Numerical index for the redirect's URL. `startTime`: The start time of
     the redirect in milliseconds, relative to navigation start.
    `duration`: The duration of the redirect in milliseconds.
    - `responseHeaders`: A list (separated by '|') of values for specific,
     pre-defined response headers, enclosed in square brackets.
    The order of headers corresponds to an internal fixed list. If a
    header is not present, its value will be empty.
 
 
 
    URL: http://localhost:5173/blog/yaml-file-defined-ai-agent-cagent/
    Bounds: {min: 435301125305, max: 435312699642}
    CPU throttling: none
    Network throttling: none
    Metrics (lab / observed):
      - LCP: 6566 ms, event: (eventKey: r-19301, ts: 435307707442),
    nodeId: 108
      - LCP breakdown:
        - TTFB: 6,289 ms, bounds: {min: 435301141341, max: 435307430566}
        - Render delay: 277 ms, bounds: {min: 435307430566, max:
    435307707442}
      - CLS: 0.00
    Metrics (field / real users): n/a – no data for this page in CrUX
    Available insights:
      - insight name: DocumentLatency
        description: Your first network request is the most important.
    Reduce its latency by avoiding redirects, ensuring a fast server
    response, and enabling text compression.
        relevant trace bounds: {min: 1954, max: 435307478926}
        estimated metric savings: FCP 6182 ms, LCP 6182 ms
        estimated wasted bytes: 237.4 kB
        example question: How do I decrease the initial loading time of my
     page?
        example question: Did anything slow down the request for this
    document?
      - insight name: LCPBreakdown
        description: Each [subpart has specific improvement
    strategies](https://web.dev/articles/optimize-lcp#lcp-breakdown).
    Ideally, most of the LCP time should be spent on loading the
    resources, not within delays.
        relevant trace bounds: {min: 435301141341, max: 435307707442}
        example question: Help me optimize my LCP score
        example question: Which LCP phase was most problematic?
        example question: What can I do to reduce the LCP time for this
    page load?
      - insight name: NetworkDependencyTree
        description: [Avoid chaining critical requests](https://developer.
    chrome.com/docs/lighthouse/performance/critical-request-chains) by
    reducing the length of chains, reducing the download size of
    resources, or deferring the download of unnecessary resources to
    improve page load.
        relevant trace bounds: {min: 435301143791, max: 435307875467}
        example question: How do I optimize my network dependency tree?
      - insight name: DOMSize
        description: A large DOM can increase the duration of style
    calculations and layout reflows, impacting page responsiveness. A
    large DOM will also increase memory usage. [Learn how to avoid an
    excessive DOM size](https://developer.chrome.com/docs/lighthouse/perfo
    rmance/dom-size/).
        relevant trace bounds: {min: 435307502075, max: 435307635893}
        example question: How can I reduce the size of my DOM?
      - insight name: ThirdParties
        description: 3rd party code can significantly impact load
    performance. [Reduce and defer loading of 3rd party
    code](https://web.dev/articles/optimizing-content-efficiency-loading-t
    hird-party-javascript/) to prioritize your page's content.
        relevant trace bounds: {min: 435307448442, max: 435307693850}
        example question: Which third parties are having the largest
    impact on my page performance?
      - insight name: ForcedReflow
        description: A forced reflow occurs when JavaScript queries
    geometric properties (such as `offsetWidth`) after styles have been
    invalidated by a change to the DOM state. This can result in poor
    performance. Learn more about [forced reflows](https://developers.goog
    le.com/web/fundamentals/performance/rendering/avoid-large-complex-layo
    uts-and-layout-thrashing#avoid-forced-synchronous-layouts) and
    possible mitigations.
        relevant trace bounds: {min: 435307799228, max: 435307859520}
        example question: How can I avoid forced reflows and layout
    thrashing?
        example question: What is forced reflow and why is it problematic?

⏺ パフォーマンス分析結果
 
  http://localhost:5173/blog/yaml-file-defined-ai-agent-cagent/
  のパフォーマンスに重大な問題があります：
 
  主要な問題
 
  1. 非常に遅いLCP (Largest Contentful Paint): 6,566ms
    - 推奨値は2.5秒以下ですが、2倍以上遅い
  2. TTFB (Time to First Byte)が非常に遅い: 6,289ms (LCP時間の95.8%)
    - サーバーレスポンスに6秒以上かかっている
    - 開発環境での異常に遅いレスポンス
  3. HTMLファイルサイズが大きい: 354,335バイト (約346KB)
    - 圧縮されていない
    - 一般的なHTMLページとしては大きすぎる
 
  特定された問題
 
  - Document Latency: サーバーが600ms以下で応答していない（実際は6秒超）
  - 圧縮未適用: レスポンスヘッダーにgzipやbrotliの圧縮が設定されていない
  - 第三者スクリプト: Google Tag Manager (201.4kB) が追加の負荷
 
  推奨改善策
 
  1. 開発サーバーの調査: localhost:5173での異常に遅いレスポンスの原因調査
  2. 圧縮の有効化: 本番環境でgzip/brotli圧縮を設定
  3. HTMLサイズの最適化: 大きなインラインスタイルやスクリプトの削減
  4. 第三者スクリプトの最適化: Google Analytics の遅延読み込み
 
  現在の開発環境では、サーバーレスポンスが通常の数十倍遅いため、本番環境で
  の検証も必要です。