Performance 2025 chapter (#4334)

* Added Introduction

* Introduction: fixed urls

* Introduction: fixed sentence

* CWV Summary: Init

* CWV: added figure markup

* Image folder: temp

* CWV: image markup

* CWV: image markdown

Add figure markup for Core Web Vitals data visualization.

* CWV: uploaded files

* Visual Stability: Init

* CLS: images markdown

* CLS images

* CLS: chart data fix

Updated the sheets_gid for the good CLS chart and added a new figure markup for the monthly trend of websites with good CLS by device.

* CWV: gid fix

* Add figure for unload handler usage by rank and device

Added figure markup for unload handler usage statistics in 2025.

* Add conclusion on visual stability improvements

Added a conclusion section summarizing visual stability improvements and areas for further optimization.

* Added Interactivity Content

* INP: Fixed excel links

* Added Interactivity Images

* Update performance.md with CWV insights and new sections

Refine the discussion on CWV data, emphasizing loading performance, interactivity, and visual stability. Add sections for Loading Speed, Early Hints, Speculation Rules, and Conclusion as TODOs.

* Add TODO sections for Images and Animation

Added sections for Images and Animation with TODO notes.

* Enhance 'Loading Speed' section with FCP and TTFB data

Expanded the 'Loading Speed' section to include detailed metrics on First Contentful Paint (FCP) and Time to First Byte (TTFB), along with performance improvements for 2024 and 2025.

* Revise Performance chapter metadata and content

Updated authors, reviewers, and analysts for the Performance chapter. Added a section on data sources and revised content for clarity and completeness.

* Enable chapter

* Delete src/static/images/2025/performance/dummy.md

* Revise performance.md for clarity and updates

Updated authors and reviewers list, improved text clarity, and refined sections on Cumulative Layout Shift (CLS) and unload handler usage.

* Update SQL file references in performance.md

Updated SQL file references for various charts in the performance report, replacing 'TODO' with specific SQL file names for better clarity and data handling.

* Added BFCache insights

Updated statistics and insights on unload handler usage and Cache-Control directives affecting BFCache eligibility. Added figures and clarified trends from 2024 to 2025.

* Revise data sources section in performance chapter

Updated the section on data sources and methodology to provide details on the data collection process, including the use of HTTP Archive and Chrome UX Report.

* Placeholder for what's new

* Document Early Hints feature and its adoption

Added detailed information about Early Hints, including its overview, usage statistics, and support across browsers and servers.

* images early hints

* Fix quotes

* Update contributors

* Update contributors

* Enhance performance.md with CLS best practices

Added best practices for Cumulative Layout Shift (CLS) and addressed unsized images in the performance section. Updated statistics for mobile and desktop regarding image dimensions and their impact on layout stability.

* Images for CLS Best practices

* Refine performance metrics and Core Web Vitals section

Review of Introduction, Core Web Vitals Summary, Interactivity, per Himanshu Jariyal.

* Apply suggestions from code review

Co-authored-by: Stoyan Stefanov <ssttoo@ymail.com>

* images related to images/fonts/animation

* fonts and animations details

Expanded sections on fonts and animations to address their impact on Cumulative Layout Shift (CLS). Added data on web font usage and resource hints, as well as the prevalence of non-composited animations.

* Revise Early Hints info and add Speculation Rules section

Updated the year for Akamai's Early Hints support and added an overview and usage section for Speculation Rules API.

* Fix markdown links in performance.md

* LCP images

* LCP content

* Update performance.md for clarity and updated metrics

Refine web performance metrics and descriptions for clarity and accuracy. Update statistics and insights for mobile and desktop performance improvements.

* Refine Early Hints section for clarity and conciseness

* Fix link and enhance Core Web Vitals section formatting

Updated the performance chapter to fix a broken link and improve the formatting of Core Web Vitals descriptions.

* edits based on TODO

* code review edits

* Update performance.md

* Update performance.md

* Enhance conclusion section with performance analysis

Added a conclusion summarizing the analysis of web performance trends, highlighting improvements in mobile interactivity, the adoption of new standards, and ongoing challenges in web performance basics.

* Refactor performance.md for clarity and updates

Removed duplicate sentence about the Web Almanac performance chapter and added mention of Early Hints and Speculation Rules.

* add what makes good CWV

* Update performance.md to reflect changes in unload usage

* Fix formatting and update support details for Early Hints

* Rephrase sentence about Early Hints usage in 2025

* Revise performance chapter details and metrics

Updated performance chapter metadata and improved author bios. Revised performance metrics and statistics for clarity and accuracy.

* make more factual, follow author/editor guides

Updated the performance chapter for the 2025 Web Almanac, refining descriptions and statistics related to Core Web Vitals, including improvements in mobile and desktop performance metrics, and adjustments in featured quotes and statistics.

* Refine language and update performance metrics section

Updated language for clarity and consistency in the performance.md file, including adjustments to phrasing and the addition of new performance features.

* nit: code review fix

* fix: missing unload handler image

* fix missing image: speculation rules

* Update src/content/en/2025/performance.md

Co-authored-by: Tanner Hodges <tannerhodges@hey.com>

* 62.28 to 62.38

Updated the percentage of mobile pages failing to set explicit dimensions on images from 62.28% to 62.38%.

* explain U curve in mobile CWV

Updated analysis of Core Web Vitals performance across mobile and desktop sites, highlighting the U-shaped pattern in site popularity and performance investment.

* Revised metadata field descriptions

* Fix chart URL in CWV

Updated the chart URL for the Core Web Vitals performance data.

* Improve performance.md with updated links

Updated links to Early Hints and Speculation Rules for clarity.

* improved flow - CWV Summary and FCP mid

Updated performance metrics for Core Web Vitals, detailing improvements in mobile and desktop performance from 2023 to 2025. Added insights on loading speed, interactivity, and visual stability, along with the impact of cached resources on secondary page navigations.

* FCP reviewed

Added insights on TTFB and FCP improvements from 2024 to 2025, highlighting the impact of server response times and render-blocking resources on performance metrics.

* Refine performance analysis conclusions for clarity

Revised language to enhance clarity and precision regarding web performance challenges and advancements.

* Fix wording for mobile impact

Corrected wording for clarity regarding the impact on mobile devices.

* Refactor LCP section for clarity and structure

Reorganized the explanation of Largest Contentful Paint (LCP) for clarity and improved flow. Separated statistics and definitions for better readability.

* Revise performance metrics and insights for 2025

Updated performance metrics and insights for Core Web Vitals, including changes in image formats and loading strategies. Improved clarity on LCP image hosting and lazy loading practices.

* Update bios

* fixed linkedin prathmesh

* LCP for clarity and updated stats

Reorganized content for clarity and updated statistics on image format usage.

* Revise loading speed conclusion with key trends summary

Summarized key trends in loading metrics, emphasizing improvements in FCP and LCP, limited adoption of new image formats, and the impact of lazy loading on load times.

* Update src/content/en/2025/performance.md

* fix build: descriptive text

* Contributors

* Links

* Retake images

* Edit chapter

* Add images

* Update stats

---------

Co-authored-by: Barry Pollard <barrypollard@google.com>
Co-authored-by: Aaron T. Grogg <aarontgrogg@gmail.com>
Co-authored-by: Stoyan Stefanov <ssttoo@ymail.com>
Co-authored-by: Tanner Hodges <tannerhodges@hey.com>
Co-authored-by: Max Ostapenko <1611259+max-ostapenko@users.noreply.github.com>

Author: 6 people

src/config/2025.json

@@ -59,8 +59,7 @@
           "part": "II",
           "chapter_number": "7",
           "title": "Performance",
-          "slug": "performance",
-          "todo": true
+          "slug": "performance"
         },
         {
           "part": "II",

src/config/contributors.json

@@ -14,6 +14,19 @@
     "twitter": "AaronGustafson",
     "website": "https://www.aaron-gustafson.com"
   },
+  "aarontgrogg": {
+    "avatar_url": "366755",
+    "bluesky": "aarontgrogg.com",
+    "github": "aarontgrogg",
+    "linkedin": "aarontgrogg",
+    "name": "Aaron T. Grogg",
+    "teams": {
+      "2025": [
+        "authors"
+      ]
+    },
+    "website": "https://aarontgrogg.com/"
+  },
   "AbbyTsai": {
     "avatar_url": "44442451",
     "github": "AbbyTsai",
@@ -2052,6 +2065,18 @@
     },
     "website": "https://hidde.blog/"
   },
+  "himanshujariyal": {
+    "avatar_url": "6078423",
+    "github": "himanshujariyal",
+    "linkedin": "himanshujariyal",
+    "name": "Himanshu Jariyal",
+    "teams": {
+      "2025": [
+        "authors"
+      ]
+    },
+    "website": "https://medium.com/@him_jar"
+  },
   "housseindjirdeh": {
     "avatar_url": "12476932",
     "github": "housseindjirdeh",
@@ -2088,6 +2113,16 @@
       ]
     }
   },
+  "hfhashmi": {
+    "avatar_url": "184349148",
+    "github": "hfhashmi",
+    "name": "Humaira",
+    "teams": {
+      "2025": [
+        "authors"
+      ]
+    }
+  },
   "iandevlin": {
     "avatar_url": "554326",
     "github": "iandevlin",
@@ -4019,12 +4054,15 @@
   "25prathamesh": {
     "avatar_url": "10120153",
     "github": "25prathamesh",
-    "linkedin": "prathameshrasam",
+    "linkedin": "prathamesh-rasam",
     "name": "Prathamesh Rasam",
     "teams": {
       "2022": [
         "analysts",
         "reviewers"
+      ],
+      "2025": [
+        "authors"
       ]
     }
   },
@@ -4780,6 +4818,21 @@
     },
     "twitter": "itsmesudheendra"
   },
+  "stoyan": {
+    "avatar_url": "51308",
+    "bluesky": "stoyan.me",
+    "github": "stoyan",
+    "linkedin": "stoyanstefanov",
+    "mastodon": "https://indieweb.social/@stoyan",
+    "name": "Stoyan Stefanov",
+    "teams": {
+      "2025": [
+        "reviewers"
+      ]
+    },
+    "twitter": "stoyanstefanov",
+    "website": "https://www.phpied.com"
+  },
   "susie-lu": {
     "name": "Susie Lu",
     "teams": {
@@ -4839,6 +4892,19 @@
     "twitter": "tameverts",
     "website": "https://speedcurve.com/"
   },
+  "tannerhodges": {
+    "avatar_url": "1619485",
+    "bluesky": "tannerhodges.bsky.social",
+    "github": "tannerhodges",
+    "name": "Tanner Hodges",
+    "teams": {
+      "2025": [
+        "analysts",
+        "reviewers"
+      ]
+    },
+    "website": "https://tannerhodges.com/"
+  },
   "thibaudcolas": {
     "avatar_url": "877585",
     "github": "thibaudcolas",