🇱🇹 Build Stuff 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, Build Stuff 👋 🇱🇹 WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED • THE 10TH OF NOVEMBER, 2022.
2. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE
3. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED 🧑🏫 @techlabs 🐦 @ythecombinator 👨💻 @medallia ↑ ALL THE LINKS! 🤓
4. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED ↑ ALL THE LINKS! 🤓 🍺 DEEP DIVE! LET’S DISCUSS MORE IN THE AFTER CONF!
5. Why am I here? WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
6. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE
7. WEB PERFORMANCE STUFF YOU ALREADY KNOW MATHEUS ALBUQUERQUE
8. ↝ HTTP/2 ↝ COMPRESS JAVASCRIPT (E.G. WITH BROTLI/ZSTD) AND USE IMAGE CDNS (40–80% SAVINGS) ↝ OPTIMIZE THIRD-PARTIES (DEFER/REPLACE/ UPDATE THEM) ↝ WORKERS TO OFF-LOAD THE MAIN THREAD YOU ALREADY KNOW…
9. — HTTPS://WWW.PATTERNS.DEV YOU ALREADY KNOW…
10. — HTTPS://WWW.PATTERNS.DEV YOU ALREADY KNOW…
11. Å
12. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
13. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
14. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
15. Å FIXING WEB PERFORMANCE
16. Å FIXING WEB PERFORMANCE
17. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
18. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
19. Measuring WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
20. #QUESTION 🤔 What does it mean to be fast?
21. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
22. #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.
23. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED If you were to summarize web performance in one metric, what’d be your pick?
24. 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 ↝ SWAG 👕 OTHERS ↝ STICKERS 💅
26. Å
27. #PROTIP💡 A lot of loading metrics don't capture user experience. We need to think about our metrics in terms of what matters.
28. #QUOTE 🦄 "My app loads in n seconds…" — Front-End Engineers, ca. 2022
30. #PROTIP💡 Load metrics are not a single number.
31. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
32. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED If you were to summarize web performance in one metric, what’d be your pick?
33. 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?
34. #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.
35. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Jean-Antoine Nollet
36. ↝ 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
37. #PROTIP💡 Browsers now provide us with many apis to fetch performance metrics that help site owners make sites faster.
38. WEB PERFORMANCE STUFF YOU ALREADY KNOW MATHEUS ALBUQUERQUE
39. WEB PLATFORM PERF APIS I DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE
40. Measuring with the platform WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
41. 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
42. 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
43. ↝ CANCEL NETWORK REQUESTS AND OTHER TIME- BASED EVENTS ↝ FETCH INCOMPLETE MEDIA OR DOWNLOAD THE REST OF YOUR BUNDLES USING DYNAMIC IMPORTS ↝ PAUSE VIDEOS AND CAROUSELS, IF THE USER IS NOT WATCHING THEM PAGE VISIBILITY
44. ↝ SUBSCRIBE TO PERFORMANCE-RELATED EVENTS ↝ CALLBACKS ARE GENERALLY FIRED DURING IDLE PERIODS ↝ YOU TELL THE OBSERVER WHAT TYPES OF ENTRIES TO LISTEN FOR PerformanceObserver
45. const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { console.log(entry.toJSON()); } }); observer.observe({type: 'some-entry-type'}); PerformanceObserver
46. ↝ 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
47. 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
48. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
49. Å LAYOUT INSTABILITY
50. Å LAYOUT INSTABILITY
51. 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.
52. / / 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
53. USER TIMING
54. USER TIMING + TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
55. USER TIMING + TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
56. ↝ 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
57. <img elementtiming="hero-image" /> <p elementtiming="important-paragraph">This is text I care about.</p> observer.observe({type: 'element'}); ELEMENT TIMING
58. ELEMENT TIMING + TOOLS — "ELEMENT TIMING: ONE TRUE METRIC TO RULE THEM ALL?" BY ANDY DAVIES
59. ↝ 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
60. 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
61. 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
62. 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
63. LONG TASKS
64. ↝ 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
65. LONG TASKS
66. observer.observe({type: 'longtask'}); LONG TASKS
67. 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
68. const profiler = new Profiler({ sampleInterval: 10, maxBufferSize: 10000 }); / / Do work . . . const trace = await profiler.stop(); sendProfile(trace); JS SELF-PROFILING
69. ↝ PROFILE SPECIFIC COMPLEX OPERATIONS ↝ PROFILE THIRD-PARTY SCRIPTS ↝ COMBINE WITH OTHER EVENTS/IMPORTANT METRICS, LIKE LONG TASKS OR EVENT TIMING APIS JS SELF-PROFILING
70. ↝ 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
71. ↝ FORGETTING TO UNREGISTER AN EVENT LISTENER ↝ ACCIDENTALLY CAPTURING OBJECTS FROM AN IFRAME ↝ NOT CLOSING A WORKER ↝ ACCUMULATING OBJECTS IN ARRAYS MEMORY LEAKS
72. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
73. const obj = { a: new Array(1000), b: new Array(2000) }; setInterval(() = > { console.log(obj.a); }, 1000); MEMORY LEAKS
74. performance.measureUserAgentSpecificMemory() UserAgentSpecificMemory
75. { 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 🍺
76. 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
77. 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
78. 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
79. NAVIGATION TIMING 🍺
80. / / 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 🍺
81. 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
82. Server-Timing: database;dur=123;desc="Database", templating;dur=56;desc="Template processing" SERVER TIMING
83. SERVER TIMING
84. SERVER TIMING
85. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
86. 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
87. const batteryInfo = await navigator.getBattery(); batteryInfo.addEventListener("chargingchange", listener); batteryInfo.addEventListener("chargingtimechange", listener); batteryInfo.addEventListener("dischargingtimechange", listener); batteryInfo.addEventListener("levelchange", listener); BATTERY STATUS
88. const networkInfo = navigator.connection; navigator.connection.addEventListener('change', onConnectionChange); NETWORK INFORMATION
89. NETWORK INFORMATION const networkInfo effectiveType: "4g", rtt: 200, downlink: 1.65, saveData: false, }
90. ↝ 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
91. 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
92. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
93. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
95. Improving with the platform WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
96. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Resource Hints
97. ↝ 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
98. < ! - - 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
99. < ! - - 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
100. ↝ 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
101. 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED
102. 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED FONT 1 FONT 2
103. ↝ DNS PREFETCH ⇢ WARNS THE BROWSER ABOUT THE DOMAINS IT’S GOING TO NEED TO LOOK UP ↝ PREFETCH ⇢ FETCH RESOURCES IN THE BACKGROUND AND STORE THEM IN CACHE ↝ PRERENDER ⇢ IT GOES ONE STEP FURTHER AND EXECUTES THE FILES …AND MUCH MORE!
104. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Priority Hints
105. ↝ 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
106. < ! - - 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
107. < ! - - 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
108. / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" }); PRIORITY HINTS
109. / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" }); PRIORITY HINTS
110. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Responsive Images
111. ↝ 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
112. <img src="buildStuff.png" srcset=" buildStuff-300.png 300w, buildStuff-600.png 600w, buildStuff-1200.png 1200w " /> <img src="buildStuff.png" srcset=" buildStuff-1x.png 1x, buildStuff-2x.png 2x, buildStuff-3x.png 3x " /> RESPONSIVE IMAGES
113. RESPONSIVE IMAGES <img src="buildStuff.png" srcset=" buildStuff-300.png 300w, buildStuff-600.png 600w, buildStuff-1200.png 1200w " /> <img src="buildStuff.png" srcset=" buildStuff-1x.png 1x, buildStuff-2x.png 2x, buildStuff-3x.png 3x " />
114. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Native Lazy- Loading
115. 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>
116. <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
117. #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
118. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Native Scheduler
119. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
120. NATIVE SCHEDULER ↝ A MORE ROBUST SOLUTION FOR SCHEDULING TASKS ↝ CONTROL AND SCHEDULE PRIORITIZED TASKS IN A UNITED AND FLEXIBLE WAY ↝ INTEGRATED DIRECTLY INTO THE EVENT LOOP ↝ ALIGNED WITH THE WORK OF THE REACT TEAM AND IN COOPERATION WITH GOOGLE, W3C AND OTHERS 🍺
121. 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
122. NATIVE SCHEDULER
124. ↝ CSS TRICKS (E.G. font-display: swap AND will-change) ↝ IMPORT ON VISIBILITY (USING AN IntersectionObserver) ↝ CANVAS + WORKERS = OffscreenCanvas …AND MUCH MORE! 🍺
125. ↝ 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! 🍺
126. Move Fast & Break Nothing ™ WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
127. BROWSER COMPATIBILITY PERFORMANCE OBSERVER USER TIMING LONG TASKS ELEMENT TIMING RESOURCE TIMING NAVIGATION TIMING
128. BROWSER COMPATIBILITY SERVER TIMING LAYOUT INSTABILITY JS SELF-PROFILING PAGE VISIBILITY BATTERY STATUS NETWORK INFORMATION
130. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
131. const Video = lazy(() = > import("./Video")); const Preview = lazy(() = > import("./Preview")); const networkInfo = useNetworkStatus(); const { With, Switch, Otherwise } = usePatternMatch(networkInfo); MOVE FAST & BREAK NOTHING ™
132. <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 ™
138. Why are we here? WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
139. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Browsers
140. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Which browsers are visiting our app? — APP DYNAMICS REPORT, LAST THREE MONTHS
141. BROWSER TOTAL
143. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Devices & Connection
144. #REALITYCHECK 😳 Phone users experience slow First Input Delay on 7x more websites. — Web Almanac By HTTP Archive, 2021
145. BANDWIDTH MIX — GSM ASSOCIATION, 2022
146. 6.07 (MBPS) 44.31 (MBPS) — THE STATE OF LTE BY OPEN SIGNAL, 2018 THE GLOBAL LTE PICTURE
147. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED People
148. 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?
149. #RESEARCH 📚 40% of Brits reported that they had become physically violent toward their computers. — British Psychology Society, 2009
150. #RESEARCH 📚 A 500ms delay resulted in up to a 26% increase in frustration and up to an 8% decrease in engagement. — Radware research, 2013
151. #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
152. #RESEARCH 📚 53% of mobile users abandon sites that take over 3 seconds to load. — DoubleClick, 2020
153. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Business
154. ↝ 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
155. BUSINESS OUTCOMES — AKAMAI AND CHROME RESEARCH, 2017
156. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Closing Notes
157. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED ALWAYS TRY TO CORRELATE BUSINESS METRICS WITH PERFORMANCE. #1
158. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED DON'T TAKE FAST NETWORKS, CPUS AND RAM FOR GRANTED. #2
159. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED TEST ON REAL PHONES AND NETWORKS. #3
160. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED AVOID THE OBSERVER EFFECT. #4
161. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED GET RID OF THE NOISE IN YOUR METRICS. #5
162. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED THERE'S NO SILVER BULLET. IDENTIFY YOUR CORE METRICS. #6
163. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
164. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
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166. THAT’S ALL, FOLKS! THANKS! 🤝 🇱🇹 QUESTIONS? MATHEUS ALBUQUERQUE ↑ ALL THE LINKS! 🤓 WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED