🇳🇱 Frontmania 2022 - Web Performance APIs

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, Frontmania ✋ 🇳🇱 WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED • THE 5TH OF OCTOBER, 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 THE IDEA BEHIND THIS SESSION IS HEAVILY INSPIRED BY ZENO'S SESSION BACK IN 2016.
6. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #1 SESSION BACK IN 2016.
7. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #2 45 MINUTES IS A LOT OF TIME, I KNOW… 🥱
8. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #2 LOT OF TIME, I KNOW… 🥱
9. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED #3 🤯 = DEEP DIVE, FURTHER DISCUSSIONS AFTER THE SESSION
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 ↝ COMPRESS JAVASCRIPT (E.G. WITH BROTLI) AND USE IMAGE CDNS (40–80% SAVINGS) ↝ OPTIMIZE THIRD-PARTIES (DEFER/REPLACE/ UPDATE THEM) ↝ WORKERS TO OFF-LOAD THE MAIN THREAD YOU ALREADY KNOW…
14. — HTTPS://WWW.PATTERNS.DEV YOU ALREADY KNOW…
15. — HTTPS://WWW.PATTERNS.DEV YOU ALREADY KNOW…
16. #QUESTION 🤔 We're all already doing (some of) these, right?
18. Å
19. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
20. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
21. Å — APP DYNAMICS REPORT, LAST THREE MONTHS
22. Å FIXING WEB PERFORMANCE
23. Å FIXING WEB PERFORMANCE
24. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
25. This talk presents Why am I here? Measuring Measuring (with the platform) Optimizing (with the platform) Why are we here? Closing thoughts
26. Measuring WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
27. #QUESTION 🤔 What does it mean to be fast?
28. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
29. #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.
30. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED If you were to summarize web performance in one metric, what’d be your pick?
31. 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 💅
33. Å
34. #PROTIP💡 A lot of loading metrics don't capture user experience. We need to think about our metrics in terms of what matters.
35. #QUOTE 🦄 "My app loads in n seconds…" — Front-End Engineers, ca. 2022
37. #PROTIP💡 Load metrics are not a single number.
38. #QUESTION 🤔 What does it mean to be fast? If you were to summarize web performance in one metric, what’d be your pick?
39. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED If you were to summarize web performance in one metric, what’d be your pick?
40. 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?
41. #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.
42. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Jean-Antoine Nollet
43. ↝ 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
44. #PROTIP💡 Browsers now provide us with many apis to fetch performance metrics that help site owners make sites faster.
45. WEB PERFORMANCE STUFF YOU ALREADY KNOW MATHEUS ALBUQUERQUE
46. WEB PLATFORM PERF APIS I DIDN’T KNOW EXISTED MATHEUS ALBUQUERQUE
47. Measuring with the platform WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
48. 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
49. 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
50. ↝ 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
51. ↝ SUBSCRIBE TO PERFORMANCE-RELATED EVENTS ↝ CALLBACKS ARE GENERALLY FIRED DURING IDLE PERIODS ↝ YOU TELL THE OBSERVER WHAT TYPES OF ENTRIES TO LISTEN FOR PerformanceObserver
52. const observer = new PerformanceObserver((list) = > { for (const entry of list.getEntries()) { console.log(entry.toJSON()); } }); observer.observe({type: 'some-entry-type'}); PerformanceObserver
53. ↝ 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
54. 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
55. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
56. Å LAYOUT INSTABILITY
57. Å LAYOUT INSTABILITY
58. 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.
59. / / 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
60. USER TIMING
61. USER TIMING + TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
62. USER TIMING + TOOLS — "USER TIMING AND CUSTOM METRICS" BY STEVE SOUDERS
63. ↝ 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
64. <img elementtiming="hero-image" /> <p elementtiming="important-paragraph">This is text I care about.</p> observer.observe({type: 'element'}); ELEMENT TIMING
65. ELEMENT TIMING + TOOLS — "ELEMENT TIMING: ONE TRUE METRIC TO RULE THEM ALL?" BY ANDY DAVIES
66. ↝ 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
67. 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
68. 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
69. 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
70. LONG TASKS
71. ↝ 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
72. LONG TASKS
73. observer.observe({type: 'longtask'}); LONG TASKS
74. 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
75. const profiler = new Profiler({ sampleInterval: 10, maxBufferSize: 10000 }); / / Do work . . . const trace = await profiler.stop(); sendProfile(trace); JS SELF-PROFILING
76. ↝ PROFILE SPECIFIC COMPLEX OPERATIONS ↝ PROFILE THIRD-PARTY SCRIPTS ↝ COMBINE WITH OTHER EVENTS/IMPORTANT METRICS, LIKE LONG TASKS OR EVENT TIMING APIS JS SELF-PROFILING
77. ↝ 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
78. ↝ FORGETTING TO UNREGISTER AN EVENT LISTENER ↝ ACCIDENTALLY CAPTURING OBJECTS FROM AN IFRAME ↝ NOT CLOSING A WORKER ↝ ACCUMULATING OBJECTS IN ARRAYS MEMORY LEAKS
79. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
80. const obj = { a: new Array(1000), b: new Array(2000) }; setInterval(() = > { console.log(obj.a); }, 1000); MEMORY LEAKS
81. performance.measureUserAgentSpecificMemory() UserAgentSpecificMemory
82. { 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 🤯
83. 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
84. 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
85. NAVIGATION TIMING
86. 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
87. / / 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
88. 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
89. Server-Timing: database;dur=123;desc="Database", templating;dur=56;desc="Template processing" SERVER TIMING
90. SERVER TIMING
91. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
92. 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
93. const batteryInfo = await navigator.getBattery(); batteryInfo.addEventListener("chargingchange", listener); batteryInfo.addEventListener("chargingtimechange", listener); batteryInfo.addEventListener("dischargingtimechange", listener); batteryInfo.addEventListener("levelchange", listener); BATTERY STATUS
94. const networkInfo = navigator.connection; navigator.connection.addEventListener('change', onConnectionChange); NETWORK INFORMATION
95. NETWORK INFORMATION const networkInfo effectiveType: "4g", rtt: 200, downlink: 1.65, saveData: false, }
96. ↝ 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
97. 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
98. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
99. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
101. Improving with the platform WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
102. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Resource Hints
103. ↝ 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
104. < ! - - 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
105. < ! - - 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
106. ↝ 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
107. 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED
108. 100MS 200MS 300MS 400MS 500MS 600MS 700MS HTML CSS FONT 1 FONT 2 FONTS START LOADING FONTS RENDERED FONT 1 FONT 2
109. ↝ 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!
110. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Priority Hints
111. ↝ 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
112. < ! - - 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
113. < ! - - 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
114. / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" }); PRIORITY HINTS
115. / / Important validation data const user = await fetch("/user"); / / Less important content data const relatedPosts = await fetch("/posts/suggested", { priority: "low" }); PRIORITY HINTS
116. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Responsive Images
117. ↝ 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
118. <img src="frontmania.png" srcset=" frontmania-300.png 300w, frontmania-600.png 600w, frontmania-1200.png 1200w " /> <img src="frontmania.png" srcset=" frontmania-1x.png 1x, frontmania-2x.png 2x, frontmania-3x.png 3x " /> RESPONSIVE IMAGES
119. RESPONSIVE IMAGES <img src="frontmania.png" srcset=" frontmania-300.png 300w, frontmania-600.png 600w, frontmania-1200.png 1200w " /> <img src="frontmania.png" srcset=" frontmania-1x.png 1x, frontmania-2x.png 2x, frontmania-3x.png 3x " />
120. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Native Lazy- Loading
121. 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>
122. <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
123. #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
124. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Native Scheduler
125. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
126. 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
127. NATIVE SCHEDULER
129. ↝ CSS TRICKS (E.G. font-display: swap AND will-change) ↝ IMPORT ON VISIBILITY (USING AN IntersectionObserver) ↝ CANVAS + WORKERS = OffscreenCanvas …AND MUCH MORE!
130. ↝ 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!
131. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
132. SERVICES & OSS
133. #PROTIP 💡 Start with observability services or libraries like web-vitals. Then create your own abstractions on top of the web (e.g. React hooks).
134. Move Fast & Break Nothing ™ WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
135. BROWSER COMPATIBILITY PERFORMANCE OBSERVER USER TIMING LONG TASKS ELEMENT TIMING RESOURCE TIMING NAVIGATION TIMING
136. BROWSER COMPATIBILITY SERVER TIMING LAYOUT INSTABILITY JS SELF-PROFILING PAGE VISIBILITY BATTERY STATUS NETWORK INFORMATION
138. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
139. const Video = lazy(() = > import("./Video")); const Preview = lazy(() = > import("./Preview")); const networkInfo = useNetworkStatus(); const { With, Switch, Otherwise } = usePatternMatch(networkInfo); MOVE FAST & BREAK NOTHING ™
140. <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 ™
146. Why are we here? WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
147. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Browsers
148. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Which browsers are visiting our app? — APP DYNAMICS REPORT, LAST THREE MONTHS
149. BROWSER TOTAL
151. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Devices & Connection
152. #REALITYCHECK 😳 Phone users experience slow First Input Delay on 7x more websites. — Web Almanac By HTTP Archive, 2021
153. BANDWIDTH MIX — GSM ASSOCIATION, 2022
154. 6.07 (MBPS) 44.31 (MBPS) — THE STATE OF LTE BY OPEN SIGNAL, 2018 THE GLOBAL LTE PICTURE
155. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED People
156. 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?
157. #RESEARCH 📚 40% of Brits reported that they had become physically violent toward their computers. — British Psychology Society, 2009
158. #RESEARCH 📚 A 500ms delay resulted in up to a 26% increase in frustration and up to an 8% decrease in engagement. — Radware research, 2013
159. #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
160. #RESEARCH 📚 53% of mobile users abandon sites that take over 3 seconds to load. — DoubleClick, 2020
161. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Business
162. ↝ 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
163. BUSINESS OUTCOMES — AKAMAI AND CHROME RESEARCH, 2017
164. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED Closing Notes
165. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED ALWAYS TRY TO CORRELATE BUSINESS METRICS WITH PERFORMANCE. #1
166. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED DON'T TAKE FAST NETWORKS, CPUS AND RAM FOR GRANTED. #2
167. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED TEST ON REAL PHONES AND NETWORKS. #3
168. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED AVOID THE OBSERVER EFFECT. #4
169. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED GET RID OF THE NOISE IN YOUR METRICS. #5
170. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED THERE'S NO SILVER BULLET. IDENTIFY YOUR CORE METRICS. #6
171. We’re hiring! 🗺 Mostly in… 🇺🇸🇲🇽🇦🇷🇺🇾🇪🇸🇨🇿🇮🇱🇮🇳
172. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
173. WEB PERFORMANCE APIS YOU (PROBABLY) DIDN'T KNOW EXISTED
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175. THAT’S ALL, FOLKS! THANKS! QUESTIONS? MATHEUS ALBUQUERQUE