🇳🇴 NDC Oslo 2022

ℹ️ Web performance APIs you (probably) didn't know existed

Responsiveness to interaction is crucial for our apps and you’ve probably heard about the amazing tools we have to measure web performance. But did you know there are many performance APIs native to the Web Platform?

In this talk, we’ll see how to leverage the power of some of them to reliably measure responsiveness and correctly identify culprits for bad experiences.

Transcript

1. Hello, NDC Oslo 🙋 🇳🇴 🌍 WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED • THE 28TH OF SEPTEMBER, 2022.
2. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE
3. Å I’M MATHEUS 🙋 ↝ @YTHECOMBINATOR ON THE WEB ↝ SR. SOFTWARE ENGINEER @MEDALLIA ↝ MENTOR @TECHLABS
4. Disclaimers WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
5. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #1 🤯 = FURTHER DISCUSSIONS AFTER THE SESSION
6. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #2 60 MINUTES IS A LOT OF TIME, I KNOW… 🥱
7. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #2 LOT OF TIME, I KNOW… 🥱
8. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #3 THE IDEA BEHIND THIS SESSION IS HEAVILY INSPIRED BY ZENO'S SESSION BACK IN 2016.
9. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #3 SESSION BACK IN 2016.
10. Why am I here? WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
11. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE
12. WEB PERFORMANCE STUFF YOU ALREADY KNOW MATHEUS ALBUQUERQUE
13. ↝ HTTP/2 (REQ/RES MULTIPLEXING; EFFICIENT COMPRESSION; REQUEST PRIORITIZATION; SERVER PUSH) ↝ COMPRESS JAVASCRIPT (E.G. WITH BROTLI) ↝ IMAGE CDNS (40–80% SAVINGS; LESS WORK WITH TRANSFORMATION, OPTIMIZATION, AND DELIVERY) YOU ALREADY KNOW…
14. ↝ OPTIMIZE THIRD-PARTIES (DEFER/REPLACE/ UPDATE THEM; TRY EXPERIMENTAL IDEAS) ↝ PRPL PATTERN (PUSH CRITICAL RESOURCES → RENDER THE INITIAL ROUTE ASAP → PRE-CACHE IN BACKGROUND → LAZILY LOAD OTHER STUFF) ↝ WORKERS TO OFF-LOAD THE MAIN THREAD YOU ALREADY KNOW…
15. — HTTPS://WWW.PATTERNS.DEV YOU ALREADY KNOW…
16. — HTTPS://WWW.PATTERNS.DEV YOU ALREADY KNOW…
17. — HTTPS://WWW.PATTERNS.DEV YOU ALREADY KNOW…
18. YOU ALREADY KNOW…
19. #QUESTION 🤔 We're all already doing (some of) these, right?
21. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
23. Å
24. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
25. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
26. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
27. Å FIXING WEB PERFORMANCE
28. Å FIXING WEB PERFORMANCE
29. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
30. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
31. Measuring WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
32. #QUESTION 🤔 What does it mean to be fast?
33. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
34. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick? e.g. load time, responsiveness, etc.
35. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED If you were to summarize web performance in one metric, what’d be your pick?
36. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED If you were to summarize web performance in one metric, what’d be your pick? 1st/2nd/3rd ANSWERS ↝ REACT BRUSSELS DISCOUNT CODE 🇧🇪 OTHERS ↝ STICKERS 💅
37. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
39. Å
40. #PROTIP💡 A lot of loading metrics don't capture user experience. We need to think about our metrics in terms of what matters.
41. #QUOTE 🦄 "My app loads in n seconds…" — Front-End Engineers, ca. 2022
43. #PROTIP💡 Load metrics are not a single number.
44. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
45. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED If you were to summarize web performance in one metric, what’d be your pick?
46. MEASURING PERCEIVED LOAD SPEED HOW QUICKLY A PAGE CAN LOAD AND RENDER ALL OF ITS VISUAL ELEMENTS TO THE SCREEN LOAD RESPONSIVENESS HOW QUICKLY A PAGE CAN LOAD/RUN ANY REQUIRED JS IN ORDER FOR COMPONENTS TO RESPOND TO USER INTERACTION RUNTIME RESPONSIVENESS AFTER THE PAGE LOAD, HOW QUICKLY CAN THE PAGE RESPOND TO USER INTERACTION? SMOOTHNESS DO TRANSITIONS & ANIMATIONS RENDER AT A CONSISTENT FRAME RATE AND FLOW FLUIDLY?
47. #PROTIP💡 The only way to truly know how your site performs for your users is to actually measure its performance as those users are loading and interacting with it.
48. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Jean-Antoine Nollet
49. ↝ THE FIRST EVER RUM EXPERIMENT IN 1746 ↝ HE GATHERED ˜200 MONKS IN CIRCUMFERENCE, WIRED USING IRON, AND DISCHARGED A BATTERY THROUGH THE HUMAN CHAIN ↝ HE WAS TESTING THE LATENCY OF AN ELECTRIC SIGNAL WITH REAL USERS JEAN-ANTOINE NOLLET
50. #PROTIP💡 Browsers now provide us with many apis to fetch performance metrics that help site owners make sites faster.
51. WEB PERFORMANCE STUFF YOU ALREADY KNOW MATHEUS ALBUQUERQUE
52. WEB PLATFORM PERF APIS I DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE
53. Measuring with the platform WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
54. MEASUREMENT APIS GENERAL STUFF DOMHighResTimeStamp, PerformanceObserver, PAGE VISIBILITY API & LAYOUT INSTABILITY API PROFILING LONG TASKS API, UserAgentSpecificMemory & JS SELF- PROFILING API TIMING USER TIMING, ELEMENT TIMING. EVENT TIMING, RESOURCE TIMING, NAVIGATION TIMING & SERVER TIMING SENSORS BATTERY STATUS & NETWORK INFORMATION
55. GENERAL STUFF DOMHighResTimeStamp MICROSECOND RESOLUTION & BASED ON THE TIME AT WHICH THE USER NAVIGATED TO THE PAGE LAYOUT INSTABILITY ALL LAYOUT SHIFT EVENTS ON A PAGE PerformanceObserver SUBSCRIBE TO PERFORMANCE-RELATED EVENTS PAGE VISIBILITY KNOW WHEN A DOCUMENT BECOMES VISIBLE OR HIDDEN
56. document.hidden; document.visibilityState; document.addEventListener("visibilitychange",() = > { if(document.visibilityState==="hidden"){ console.log("This window is hidden") } else{ console.log("This window is visible") } }) PAGE VISIBILITY
57. ↝ CANCEL NETWORK REQUESTS AND OTHER TIME- BASED EVENTS ↝ SUSPEND WEB SOCKETS AND EVENTSOURCE CONNECTIONS ↝ PAUSE VIDEOS AND CAROUSELS, IF THE USER IS NOT WATCHING THEM PAGE VISIBILITY
58. ↝ FETCH INCOMPLETE MEDIA TO GIVE A COMPLETELY LOADED SITE WHEN ACTIVE AGAIN ↝ DOWNLOAD THE REST OF YOUR BUNDLES USING DYNAMIC IMPORTS (AND CACHE THEIR ASSETS) ↝ MONITOR THE USER’S BEHAVIOR ↝ THROTTLE TIMERS LIKE setTimeout() PAGE VISIBILITY
59. ↝ SUBSCRIBE TO PERFORMANCE-RELATED EVENTS ↝ CALLBACKS ARE GENERALLY FIRED DURING IDLE PERIODS ↝ YOU TELL THE OBSERVER WHAT TYPES OF ENTRIES TO LISTEN FOR PerformanceObserver
60. const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { console.log(entry.toJSON()); } }); observer.observe({type: 'some-entry-type'}); PerformanceObserver
61. ↝ MANY WEBSITES HAVE DOM ELEMENTS SHIFTING AROUND DUE TO CONTENT LOADING ASYNCHRONOUSLY ↝ THIS API GIVES US A LIST OF ALL LAYOUT SHIFT EVENTS ON A PAGE LAYOUT INSTABILITY
62. const observer = new PerformanceObserver((list) = > { const entries = list.getEntries(); / / Shifts that are not preceded by input events const nonInputEntries = entries.filter((entry) = > !entry.hadRecentInput); for (const entry of nonInputEntries) { console.log(entry); } }); observer.observe({type: 'layout-shift'}); LAYOUT INSTABILITY
63. [ { "name": "", "entryType": "layout-shift", "startTime": 3087.2349999990547, "duration": 0, "value": 0.3422101449275362, "hadRecentInput": false, "lastInputTime": 0 } ] LAYOUT INSTABILITY
64. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
65. Å LAYOUT INSTABILITY
66. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
67. Å LAYOUT INSTABILITY
68. TIMING (1st ACT) USER TIMING ALLOWS YOU TO MARK POINTS IN TIME AND THEN MEASURE THE DURATION BETWEEN THOSE MARKS. EVENT TIMING EVENT PROCESSING TIME + TIME UNTIL THE NEXT FRAME CAN BE RENDERED. THE BASIS FOR THE FID METRIC. ELEMENT TIMING MEASURE THE RENDER TIME OF SPECIFIC ELEMENTS. THE BASIS FOR THE LCP METRIC.
69. / / Record the time i m m ediately before running a task performance.mark('myTask:start'); await doMyTask(); / / Record the time i m m ediately after running a task performance.mark('myTask:end'); / / Measure the delta between the start and end of the task performance.measure('myTask', 'myTask:start', ‘myTask:end'); observer.observe({type: 'measure'}); USER TIMING
70. USER TIMING
71. EXAMPLE CUSTOM METRICS ↝ STYLESHEETS DONE BLOCKING ↝ SCRIPTS DONE BLOCKING ↝ FONTS LOADED ↝ TEXT DISPLAYED USER TIMING
72. USER TIMING + TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
73. USER TIMING + TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
74. ↝ ALLOWS YOU TO MEASURE THE RENDER TIME OF SPECIFIC ELEMENTS ↝ USEFUL FOR KNOWING WHEN THE LARGEST IMAGE OR TEXT BLOCK WAS PAINTED TO THE SCREEN ↝ THE BASIS FOR THE LARGEST CONTENTFUL PAINT (LCP) METRIC ELEMENT TIMING
75. <img elementtiming="hero-image" /> <p elementtiming="important-paragraph">This is text I care about.</p> observer.observe({type: 'element'}); ELEMENT TIMING
76. { "name": "http://localhost:3030/public/hero.png", "id": "hero-image", "entryType": "element", "startTime": 90.68500006105751, "duration": 0, "identifier": "some-identifier", "naturalHeight": 73, "naturalWidth": 70, "intersectionRect": { "x": 253, "y": 30, "width": 71, "height": 73 } } ELEMENT TIMING
77. ELEMENT TIMING + TOOLS — "ELEMENT TIMING: ONE TRUE METRIC TO RULE THEM ALL?" BY ANDY DAVIES
78. ELEMENT TIMING + TOOLS
79. ↝ USEFUL TO MEASURE THE EVENT PROCESSING TIME AS WELL AS THE TIME UNTIL THE NEXT FRAME CAN BE RENDERED ↝ EXPOSES A NUMBER OF TIMESTAMPS IN THE EVENT LIFECYCLE ↝ THE BASIS FOR THE FIRST INPUT DELAY METRIC EVENT TIMING
80. const observer = new PerformanceObserver((entryList) = > { const firstInput = entryList.getEntries()[0]; const firstInputDelay = firstInput.processingStart - firstInput.startTime; / / Measure the time it takes to run all event handlers const firstInputProcessingTime = firstInput.processingEnd - firstInput.processingStart; / / Measure the entire duration of the event const firstInputDuration = firstInput.duration; }); observer.observe({type: 'first-input'}); EVENT TIMING
81. MEASURE THE LATENCY… ↝ FROM A CLICK UNTIL WE REORDER CONTENT ON A TABLE ↝ TO DRAG A SLIDER TO FILTER SOME DATA ↝ FOR A FLYOUT TO APPEAR WHEN HOVERING A MENU ITEM EVENT TIMING
82. PROFILING LONG TASKS API REPORTS TASKS THAT TAKES LONGER THAN 50 MS AND IT'S THE BASIS FOR TTI AND TBT METRICS JS SELF-PROFILING API PROFILE SPECIFIC COMPLEX OPERATIONS AND IDENTIFY HOT SPOTS USING A SAMPLING PROFILER UserAgentSpecificMemory DETECT MEMORY LEAKS IN APPS THAT HANDLE A HUGE VOLUME OF DATA
83. ↝ REPORTS TASKS THAT TAKES LONGER THAN 50 MS ↝ USEFUL TO TRACK WHEN THE BROWSER'S MAIN THREAD IS BLOCKED ↝ THE BASIS FOR TIME TO INTERACTIVE (TTI) AND TOTAL BLOCKING TIME (TBT) METRICS LONG TASKS
84. LONG TASKS
85. LONG TASKS
86. observer.observe({type: 'longtask'}); LONG TASKS
87. observer.observe({type: 'longtask'}); { name: "same-origin-descendant", entryType: "longtask", startTime: 1023.40999995591, duration: 187.19000002602115, attribution: [ { name: "unknown", entryType: "taskattribution", startTime: 0, duration: 0, containerType: "iframe", containerSrc: "child.html", containerId: "", containerName: "child1" } ] }; LONG TASKS
88. const profiler = new Profiler({ sampleInterval: 10, maxBufferSize: 10000 }); / / Do work . . . const trace = await profiler.stop(); sendProfile(trace); JS SELF-PROFILING
89. ↝ PROFILE SPECIFIC COMPLEX OPERATIONS ↝ PROFILE THIRD-PARTY SCRIPTS ↝ PROFILE THE ENTIRE PAGE LOAD PROCESS ↝ COMBINE WITH OTHER EVENTS/IMPORTANT METRICS, LIKE LONG TASKS OR EVENT TIMING APIS JS SELF-PROFILING
90. ↝ MEASURES THE MEMORY USAGE AND DETECTS MEMORY LEAKS ↝ WAITS FOR THE NEXT GC AND THEN MEASURES MEMORY IMMEDIATELY AFTER THE UNNEEDED MEMORY HAS BEEN RELEASED ↝ FORCES GC IF IT DOES NOT HAPPEN FOR 20S UserAgentSpecificMemory
91. ↝ FORGETTING TO UNREGISTER AN EVENT LISTENER ↝ ACCIDENTALLY CAPTURING OBJECTS FROM AN IFRAME ↝ NOT CLOSING A WORKER ↝ ACCUMULATING OBJECTS IN ARRAYS MEMORY LEAKS
92. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
93. const obj = { a: new Array(1000), b: new Array(2000) }; setInterval(() = > { console.log(obj.a); }, 1000); MEMORY LEAKS
94. performance.measureUserAgentSpecificMemory() UserAgentSpecificMemory
95. ↝ APPS THAT HANDLE A HUGE VOLUME OF DATA ↝ REGRESSION DETECTION DURING THE ROLLOUT OF A NEW VERSION ↝ A/B TESTING TO EVALUATE MEMORY IMPACT ↝ CORRELATING MEMORY USAGE WITH USER METRICS TO UNDERSTAND THE IMPACT OF MEMORY USAGE UserAgentSpecificMemory
96. { name: "same-origin-descendant", entryType: "longtask", startTime: 1023.40999995591, duration: 187.19000002602115, attribution: [ { name: "unknown", entryType: "taskattribution", startTime: 0, duration: 0, containerType: "iframe", containerSrc: "child.html", containerId: "", containerName: "child1" } ] } { bytes: 1000000, breakdown: [ { bytes: 1000000, attribution: [ { url: "https://example.com", scope: "Window", }, ], types: ["JS", "DOM"], }, { bytes: 0, attribution: [], types: [], }, ], } { "frames": [ { "name": "Profiler" }, { "column": 0, "line": 100, "name": "", "resourceId": 0 }, { "name": "set innerHTML" }, { "column": 10, "line": 10, "name": "A", "resourceId": 1 } { "column": 20, "line": 20, "name": "B", "resourceId": 1 } ], "resources": [ "https://example.com/page", "https://example.com/app.js", ], "samples": [ { "stackId": 0, "timestamp": 161.99500000476837 }, { "stackId": 2, "timestamp": 182.43499994277954 }, { "timestamp": 197.43499994277954 }, { "timestamp": 213.32999992370605 }, { "stackId": 3, "timestamp": 228.59999990463257 }, ], "stacks": [ { "frameId": 0 }, { "frameId": 2 }, { "frameId": 3 }, { "frameId": 4, "parentId": 2 } ] } LONG TASKS SELF-PROFILING USERAGENT MEMORY 🤯
97. TIMING (2nd ACT) RESOURCE TIMING RETRIEVE AND ANALYZE DETAILED NETWORK TIMING DATA REGARDING THE LOADING SERVER TIMING COMMUNICATE PERFORMANCE METRICS ABOUT HOW TIME IS SPENT WHILE PROCESSING THE REQUEST NAVIGATION TIMING COMPLETE TIMING INFORMATION FOR NAVIGATION OF A DOCUMENT
98. Å RESOURCE TIMING 🤯
99. const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { / / If transferSize is 0, the resource was fulfilled via the cache. console.log(entry.name, entry.transferSize === 0); } }); observer.observe({type: 'resource'}); RESOURCE TIMING
100. NAVIGATION TIMING
101. const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { console.log('Time to first byte', entry.responseStart); } }); observer.observe({type: 'navigation'}); NAVIGATION TIMING
102. / / ServiceWorker startup time const workerStartupTime = entry.responseStart - entry.workerStart; / / Request time only (excluding redirects, DNS, and connection/TLS time) const requestTime = entry.responseStart - entry.requestStart; / / Response time only (download) const responseTime = entry.responseEnd - entry.responseStart; / / Request + response time const requestResponseTime = entry.responseEnd - entry.requestStart; NAVIGATION TIMING
103. Server-Timing: metric1;dur=123;desc="Metric 1", metric2;dur=456;desc="Metric 2", … SERVER TIMING
104. MEASURE ANY WORK THAT THE SERVER DOES TO COMPLETE A REQUEST: ↝ ROUTING/AUTHENTICATING THE REQUEST ↝ QUERYING DATABASES/API CALLS TO THIRD-PARTY SERVICES ↝ RUNNING CONTENT THROUGH TEMPLATING SYSTEMS SERVER TIMING
105. Server-Timing: database;dur=123;desc="Database", templating;dur=56;desc="Template processing" SERVER TIMING
106. SERVER TIMING
107. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
108. SENSORS BATTERY STATUS INFORMATION ABOUT THE POWER SOURCE, CHARGE LEVEL, AND OTHERS NETWORK INFORMATION ADAPT THE USERS’ EXPERIENCE BASED ON THE QUALITY OF THEIR CONNECTION
109. const batteryInfo = await navigator.getBattery(); batteryInfo.addEventListener("chargingchange", listener); batteryInfo.addEventListener("chargingtimechange", listener); batteryInfo.addEventListener("dischargingtimechange", listener); batteryInfo.addEventListener("levelchange", listener); BATTERY STATUS
110. const networkInfo = navigator.connection; navigator.connection.addEventListener('change', onConnectionChange); NETWORK INFORMATION
111. NETWORK INFORMATION const networkInfo effectiveType: "4g", rtt: 200, downlink: 1.65, saveData: false, }
112. ↝ SWITCH BETWEEN SERVING HIGH/LOW DEFINITION CONTENT BASED ON THE USER'S NETWORK ↝ DECIDE WHETHER TO PRELOAD RESOURCES ↝ DEFER UPLOADS/DOWNLOADS WHEN USERS ARE ON A SLOW CONNECTION ↝ ADAPT TO SITUATIONS WHEN USERS ARE OFFLINE NETWORK INFORMATION
113. ↝ ENABLE OFFLINE MODE IF THE NETWORK QUALITY IS NOT GOOD ENOUGH ↝ WARN USERS THAT DOING SOMETHING OVER CELLULAR COULD COST THEM MONEY ↝ USE IT IN YOUR ANALYTICS TO GATHER DATA ON YOUR USERS' NETWORK QUALITY NETWORK INFORMATION
114. switch (connectionType) { case "4g": return <Video src={videoSrc} />; case "3g": return <Image src={imageSrc.hiRes} alt={alt} />; default: return <Image src={imageSrc.lowRes} alt={alt} />; } NETWORK INFORMATION
115. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
116. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
118. Improving with the platform WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
119. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Resource Hints
120. ↝ MANY PERFORMANCE OPTIMIZATIONS CAN BE MADE WHEN WE CAN PREDICT WHAT USERS MIGHT DO ↝ RESOURCE HINTS ARE A SIMPLE BUT EFFECTIVE WAY TO ALLOW DEVELOPERS TO HELP THE BROWSER TO STAY ONE STEP AHEAD OF THE USER AND KEEP PAGES FAST RESOURCE HINTS
121. < ! - - Preconnect - - > <link rel="preconnect" href="https://fonts.gstatic.com"> <link rel="preconnect" href="https://scripts.example.com"> < ! - - Preloading - - > <link rel="preload" href="https://example.com/fonts/font.woff"> < ! - - DNS Prefetch - - > <link rel="dns-prefetch" href="https://fonts.gstatic.com"> <link rel="dns-prefetch" href="https://images.example.com"> < ! - - Prefetch - - > <link rel="prefetch" href="/uploads/images/pic.png"> <link rel="prefetch" href="https://example.com/news/?page=2"> < ! - - Prerender - - > <link rel="prerender" href="https://example.com/news/?page=2"> RESOURCE HINTS
122. < ! - - Preconnect - - > <link rel="preconnect" href="https://fonts.gstatic.com"> <link rel="preconnect" href="https://scripts.example.com"> < ! - - Preloading - - > <link rel="preload" href="https://example.com/fonts/font.woff"> < ! - - DNS Prefetch - - > <link rel="dns-prefetch" href="https://fonts.gstatic.com"> <link rel="dns-prefetch" href="https://images.example.com"> < ! - - Prefetch - - > <link rel="prefetch" href="/uploads/images/pic.png"> <link rel="prefetch" href="https://example.com/news/?page=2"> < ! - - Prerender - - > <link rel="prerender" href="https://example.com/news/?page=2"> RESOURCE HINTS
123. ↝ IT ALLOWS THE BROWSER TO SETUP EARLY CONNECTIONS BEFORE THE REQUEST IS ACTUALLY SENT TO THE SERVER. THIS INCLUDES: • TLS NEGOTIATIONS • TCP HANDSHAKES ↝ ELIMINATES ROUNDTRIP LATENCY PRECONNECT
124. 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED
125. 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED FONT 1 FONT 2
126. ↝ IT WARNS THE BROWSER ABOUT THE DOMAINS IT’S GOING TO NEED TO LOOK UP ↝ THIS ENABLES THE IT TO DO MORE WORK IN PARALLEL, REDUCING THE OVERALL LOAD TIME ↝ USE IT WHEN YOUR PAGE USES RESOURCES FROM A DIFFERENT DOMAIN DNS PREFETCH
127. ↝ FETCH RESOURCES IN THE BACKGROUND (IDLE TIME) AND STORE THEM IN CACHE ↝ USE IT WHEN YOU HAVE A REASONABLE AMOUNT OF CERTAINTY ↝ THIS SHOULD BE WEIGHED AGAINST THE RISK OF WASTING RESOURCES PREFETCH
128. ↝ IT GOES ONE STEP FURTHER AND EXECUTES THE FILES ↝ IT DOES PRETTY MUCH ALL THE WORK REQUIRED TO DISPLAY THE PAGE, MAKING ITS LOAD FEEL INSTANTANEOUS ↝ THE GAMBLE IS EVEN GREATER HERE PRERENDER
129. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Priority Hints
130. ↝ INCREASE THE PRIORITY OF THE LCP IMAGE ↝ LOWER THE PRIORITY OF ABOVE-THE-FOLD IMAGES AND PRELOADED RESOURCES ↝ LOWER THE PRIORITY FOR NON-CRITICAL DATA FETCHES ↝ REPRIORITIZE SCRIPTS PRIORITY HINTS
131. < ! - - Increase the priority of the LCP image - - > <img src="image.jpg" fetchpriority="high" /> < ! - - Lower the priority of above-the-fold images - - > <ul class="carousel"> <img src="img/carousel-1.jpg" fetchpriority="high" /> <img src="img/carousel-2.jpg" fetchpriority="low" /> <img src="img/carousel-3.jpg" fetchpriority="low" /> </ul> < ! - - Reprioritize scripts - - > <script src="async_but_important.js" async fetchpriority="high"></script> <script src="blocking_but_unimportant.js" fetchpriority="low"></script> PRIORITY HINTS
132. < ! - - Increase the priority of the LCP image - - > <img src="image.jpg" fetchpriority="high" /> < ! - - Lower the priority of above-the-fold images - - > <ul class="carousel"> <img src="img/carousel-1.jpg" fetchpriority="high" /> <img src="img/carousel-2.jpg" fetchpriority="low" /> <img src="img/carousel-3.jpg" fetchpriority="low" /> </ul> < ! - - Reprioritize scripts - - > <script src="async_but_important.js" async fetchpriority="high"></script> <script src="blocking_but_unimportant.js" fetchpriority="low"></script> PRIORITY HINTS
133. / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" }); PRIORITY HINTS
134. / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" }); PRIORITY HINTS
135. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Responsive Images
136. ↝ IMAGES FOR DESKTOP AND TABLET CAN BE ˜2-4X LARGER THAN THE MOBILE ONES. ↝ WITH srcset, THE BROWSER WON'T DOWNLOAD THE LARGER IMAGES UNLESS THEY'RE NEEDED. THAT SAVES BANDWIDTH. RESPONSIVE IMAGES
137. <img src="ndc_oslo_logo.png" srcset=" ndc_oslo_logo-300.png 300w, ndc_oslo_logo-600.png 600w, ndc_oslo_logo-1200.png 1200w " /> <img src="ndc_oslo_logo.png" srcset=" ndc_oslo_logo-1x.png 1x, ndc_oslo_logo-2x.png 2x, ndc_oslo_logo-3x.png 3x " /> RESPONSIVE IMAGES
138. <img src="ndc_oslo_logo.png" srcset=" ndc_oslo_logo-300.png 300w, ndc_oslo_logo-600.png 600w, ndc_oslo_logo-1200.png 1200w " /> <img src="ndc_oslo_logo.png" srcset=" ndc_oslo_logo-1x.png 1x, ndc_oslo_logo-2x.png 2x, ndc_oslo_logo-3x.png 3x " /> RESPONSIVE IMAGES
139. <img src="ndc_oslo_logo.png" srcset=" ndc_oslo_logo-300.png 300w, ndc_oslo_logo-600.png 600w, ndc_oslo_logo-1200.png 1200w " /> <img src="ndc_oslo_logo.png" srcset=" ndc_oslo_logo-1x.png 1x, ndc_oslo_logo-2x.png 2x, ndc_oslo_logo-3x.png 3x " /> RESPONSIVE IMAGES
140. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Native Lazy- Loading
141. NATIVE LAZY-LOADING <img src="image.png" loading="lazy" alt="…" width="200" height="200"> <iframe src="https://example.com" loading="lazy" width="600" height="400"></iframe>
142. <img src="image.png" loading="lazy" alt="…" width="200" height="200"> <iframe src="https://example.com" loading="lazy" width="600" height="400"></iframe> NATIVE LAZY-LOADING
145. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
146. #PROTIP 💡 Lazy-loading iframes can lead to 2-3% median data savings, 1-2% FCP reductions, and 2% FID improvements at the 95th percentile. — Chrome team’s research, 2019
147. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Native Scheduler
148. SCHEDULING & THE WEB WE HAVE A FEW SCHEDULING PRIMITIVES: ↝ setTimeout ↝ requestAnimationFrame ↝ requestIdleCallback ↝ postMessage
149. ↝ EVERYONE SHOULD USE THE SAME SCHEDULER ↝ HAVING MORE THAN ONE SCHEDULER CAUSES RESOURCE FIGHTING ↝ WE HAVE TASKS INTERLEAVING WITH BROWSER WORK (RENDERING, GARBAGE COLLECTION) SCHEDULING & THE WEB
150. #RANT 😡 We need better and uniform scheduling primitives for the web!
151. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
152. NATIVE SCHEDULER ↝ A MORE ROBUST SOLUTION FOR SCHEDULING TASKS ↝ INTEGRATED DIRECTLY INTO THE EVENT LOOP ↝ CONTROL AND SCHEDULE PRIORITIZED TASKS IN A UNITED AND FLEXIBLE WAY ↝ ALIGNED WITH THE WORK OF THE REACT TEAM AND IN COOPERATION WITH GOOGLE, W3C AND OTHERS
153. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
154. scheduler.postTask() SCHEDULE AND CONTROL PRIORITIZING TASKS. scheduler.wait() YIELD AND RESUME AFTER SOME AMOUNT OF TIME OR PERHAPS AFTER AN EVENT HAS OCCURRED. scheduler.yield() BREAK UP LONG TASKS BY YIELDING TO THE BROWSER AND CONTINUING AFTER BEING RESCHEDULED. isInputPending() DETERMINE IF THE CURRENT TASK IS BLOCKING INPUT EVENTS. NATIVE SCHEDULER
155. scheduler.postTask() const promise = scheduler.postTask(myTask);
156. scheduler.postTask() const promise = scheduler.postTask(myTask, { priority: "user-blocking" });
157. scheduler.postTask() scheduler.postTask(() = > { console.log('NDC Oslo'); }, { delay: 10 }); scheduler.postTask(() = > { console.log('NDC Sydney'); }); scheduler.postTask(() = > { console.log('NDC Minnesota'); }); / / 'NDC Sydney' 'NDC Minnesota’ 'NDC Oslo'
158. scheduler.postTask() const controller = new TaskController({ priority: "user-blocking" }); const signal = controller.signal; console.log(signal.priority); / / 'user-blocking' console.log(signal.aborted); / / 'false' scheduler.postTask(doWork, { signal }); controller.setPriority("background"); controller.abort();
159. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
160. isInputPending() while (workQueue.length > 0) { if (navigator.scheduling.isInputPending()) { / / Stop doing work to handle any input event break; } let job = workQueue.shift(); job.execute(); }
161. isInputPending() while (workQueue.length > 0) { if (navigator.scheduling.isInputPending()) { / / Stop doing work to handle any input event break; } let job = workQueue.shift(); job.execute(); }
162. isInputPending() while (workQueue.length > 0) { if (navigator.scheduling.isInputPending(['mousedown', 'keydown'])) { / / Stop doing work to handle a mouse or key event break; } let job = workQueue.shift(); job.execute(); }
163. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
164. scheduler.yield() async function doWork() { while (true) { let hasMoreWork = doSomeWork(); if (!hasMoreWork) { return; } await scheduler.yield(); } }
165. async function doWork() { while (true) { let hasMoreWork = doSomeWork(); if (!hasMoreWork) { return; } if (!navigator.scheduling.isInputPending()) { continue; } await scheduler.yield(); } } scheduler.yield()
166. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
167. scheduler.yield() async function findInFiles(query) { for (const file of files) { await yieldOrContinue("user-visible"); for (const line of file.lines) { fuzzySearchLine(line, query); } } }
168. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
169. #QUESTION 🤔 How could we improve that?
170. function resourcefulOperation(value: number) { let newValue = String(value); for (let i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = resourcefulOperation(value); return <p>{result}</p>; }
171. function* resourcefulOperation(value: number) { let newValue = String(value); while (true) { yield; for (let i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } } const initialValue = 0; const scheduler = new Scheduler(resourcefulOperation, initialValue); function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = scheduler.performUnitOfWork(value); return <p>{result}</p>; }
172. function* resourcefulOperation(value: number) { let newValue = String(value); while (true) { yield; for (let i = 0; i < 1000000; i++) { newValue = `${value} + ${i} = ${value + i}`; } return newValue; } } const initialValue = 0; const scheduler = new Scheduler(resourcefulOperation, initialValue); function ResourcefulComponent(props: { value: number }) { const { value } = props; const result = scheduler.performUnitOfWork(value); return <p>{result}</p>; } PROMOTED TO A GENERATOR YIELDING EXECUTION DOING CONCURRENT TASKS
173. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
174. enum SchedulerState { IDLE = "IDLE", PENDING = "PENDING", DONE = "DONE", } class Scheduler<T> { state: SchedulerState; result: T; worker: (data: T) = > Generator; iterator: Generator; constructor(worker: (data: T) = > Generator, initialResult: T) { this.state = SchedulerState.IDLE; this.worker = worker; this.result = initialResult; } performUnitOfWork(data: T) { switch (this.state) { case "IDLE": this.state = SchedulerState.PENDING; this.iterator = this.worker(data); throw Promise.resolve(); case "PENDING": const { value, done } = this.iterator.next(); if (done) { this.result = value; this.state = SchedulerState.DONE; return value; } throw Promise.resolve(); case "DONE": this.state = SchedulerState.IDLE; return this.result; } } }
176. ↝ CSS TRICKS (E.G. font-display: swap AND will-change) ↝ IMPORT ON VISIBILITY (USING AN IntersectionObserver) ↝ SCHEDULING ALTERNATIVES WITH sendBeacon ↝ CANVAS + WORKERS = OffscreenCanvas …AND MUCH MORE!
177. ↝ AVOID THE INITIAL HTTP TO HTTPS REDIRECTS SO THAT PAGES LOAD FASTER USING HTTP STRICT TRANSPORT SECURITY (HSTS) ↝ SEND DATA WITHOUT EXTRA ROUND TRIPS WITH QUIC …AND MUCH MORE!
178. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
179. SERVICES & OSS
180. #PROTIP 💡 Start with observability services or libraries like web-vitals. Then create your own abstractions on top of the web (e.g. React hooks).
181. Move Fast & Break Nothing ™ WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
182. BROWSER COMPATIBILITY PERFORMANCE OBSERVER USER TIMING LONG TASKS ELEMENT TIMING RESOURCE TIMING NAVIGATION TIMING
183. BROWSER COMPATIBILITY SERVER TIMING LAYOUT INSTABILITY JS SELF-PROFILING PAGE VISIBILITY BATTERY STATUS NETWORK INFORMATION
184. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
186. MOVE FAST & BREAK NOTHING ™
187. const Video = lazy(() = > import("./Video")); const Preview = lazy(() = > import("./Preview")); const networkInfo = useNetworkStatus(); const { With, Switch, Otherwise } = usePatternMatch(networkInfo); MOVE FAST & BREAK NOTHING ™
188. <Suspense fallback={<div>Loading . . . </div>}> <With unsupported> <NetworkStatus networkInfo="unsupported" /> <Video /> </With> <With effectiveConnectionType="2g"> <NetworkStatus networkInfo="2g" /> <Preview /> </With> </Suspense> MOVE FAST & BREAK NOTHING ™
197. Why are we here? WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
198. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Browsers
199. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Which browsers are visiting our app? — APP DYNAMICS REPORT, LAST THREE MONTHS
200. BROWSER TOTAL
204. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Devices & Connection
205. #REALITYCHECK 😳 Phone users experience slow First Input Delay on 7x more websites. — Web Almanac By HTTP Archive, 2021
206. DESKTOP PHONE 0 25 50 75 100 SLOW ( > = 250MS) AVERAGE FAST (<50 MS) FIRST INPUT DELAY
207. BANDWIDTH MIX — GSM ASSOCIATION, 2022
208. HTTPS://WWW.JUMIA.COM.NG HTTPS://MOBILE.TWITTER.COM — THE COST OF JAVASCRIPT IN 2019, BY ADDY OSMANI BANDWIDTH MIX
209. 6.07 (MBPS) 44.31 (MBPS) — THE STATE OF LTE BY OPEN SIGNAL, 2018 THE GLOBAL LTE PICTURE
210. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED People
211. THE TIME IT TAKES TO LOAD A PAGE HOW EASY IT IS TO FIND WHAT I'M LOOKING FOR HOW WELL THE SITE FITS MY SCREEN HOW SIMPLE THE SITE IS TO USE HOW ATTRACTIVE THE SITE LOOKS — SPEED MATTERS, VOL. 3 HOW IMPORTANT IS SPEED?
212. #RESEARCH 📚 40% of Brits reported that they had become physically violent toward their computers. — British Psychology Society, 2009
213. #RESEARCH 📚 38% of Americans with computer issues reported that they had screamed, yelled, or physically assaulted their computers. — crucial.com research, 2013
214. #RESEARCH 📚 A 500ms delay resulted in up to a 26% increase in frustration and up to an 8% decrease in engagement. — Radware research, 2013
215. #RESEARCH 📚 Delayed web pages caused a 38% rise in mobile users' heart rates — equivalent to the anxiety of watching a horror movie alone. — Ericsson ConsumerLab neuro research, 2015
216. #RESEARCH 📚 53% of mobile users abandon sites that take over 3 seconds to load. — DoubleClick, 2020
217. #PROTIP💡 People from different parts of the world have a different threshold for frustration. — UNDERSTANDING EMOTION FOR HAPPY USERS, BY PHILIP TELLIS
218. — UNDERSTANDING EMOTION FOR HAPPY USERS, BY PHILIP TELLIS FRUSTATION INDEX
219. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Business
220. ↝ LONG TASKS DELAYED TTI ↝ AS FIRST-PAGE LONG TASK TIME INCREASED, OVERALL CONVERSION RATES DECREASED ↝ MOBILE HAD UP TO ˜12X LONGER LONG TASKS ↝ OLDER DEVICES COULD BE SPENDING HALF OF THEIR LOAD-TIME ON LONG TASKS BUSINESS OUTCOMES — AKAMAI AND CHROME RESEARCH, 2017
221. BUSINESS OUTCOMES — AKAMAI AND CHROME RESEARCH, 2017
222. ↝ THE RANGE OF BROWSERS THAT PEOPLE USE IS USUALLY WIDER THAN WE THINK ↝ ACCESS TO 4G AND 5G IS STILL (VERY) LIMITED IN SOME PARTS OF THE GLOBE ↝ 4G/5G AVAILABILITY AND 4G/5G SPEED ARE DIFFERENT METRICS WHY ARE WE HERE?
223. ↝ ANYTHING THAT SLOWS DOWN OR PREVENTS PEOPLE FROM ACCOMPLISHING THEIR GOALS WILL CAUSE FRUSTRATION ↝ PEOPLE WILL ABANDON SITES THAT CAUSE FRUSTRATION WHY ARE WE HERE?
224. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Closing Notes
225. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED ALWAYS TRY TO CORRELATE BUSINESS METRICS WITH PERFORMANCE. #1
226. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED DON'T TAKE FAST NETWORKS, CPUS AND RAM FOR GRANTED. #2
227. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED TEST ON REAL PHONES AND NETWORKS. #3
228. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED AVOID THE OBSERVER EFFECT. #4
229. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED GET RID OF THE NOISE IN YOUR METRICS. #5
230. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED THERE'S NO SILVER BULLET. IDENTIFY YOUR CORE METRICS. #6
231. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED "IN GOD WE TRUST. ALL OTHERS MUST BRING DATA." — W. EDWARDS DEMING #7
232. We’re hiring! 🗺 Mostly in… 🇺🇸🇲🇽🇦🇷🇺🇾🇪🇸🇨🇿🇮🇱🇮🇳
233. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
234. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
235. Å
236. THAT’S ALL, FOLKS! THANKS! QUESTIONS? MATHEUS ALBUQUERQUE