Frontend Web Performance - better, faster, stronger

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Frontend Web Performance better, faster, stronger @stefanjudis

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Stefan Judis Frontend Developer, Occasional Teacher, Meetup Organizer ❤ Open Source, Performance and Accessibility ❤ @stefanjudis

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Start performance tooling today PERF TOOLING www.perf-tooling.today

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I live in a bubble! (Usually)

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I live in a bubble!

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Recent MacBook Pro Recent phone with 5GB EU wide fast data plan

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Bruce Lawson previously @ Opera Where will your next customer come from?

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12 731 MILLION CHINA TOP 10 COUNTRIES WITH THE HIGHEST NUMBER OF INTERNET USERS 462 MILLION INDIA 286 MILLION USA 139 MILLION BRAZIL 132 MILLION INDONESIA 118 MILLION JAPAN 104 MILLION RUSSIA 93 MILLION NIGERIA 71 MILLION GERMANY 69 MILLION MEXICO www.internetworldstats.com/top20.htm

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Finnland France Denmark Great Britian Ireland Italy Spain Germany USA Hungary 0GB 25GB 50GB 75GB 100GB de.statista.com/infograﬁk/6188/4g-im-laendervergleich/ data with 4g for 35€ unlimited 50 40 20 10 8 7 4 2 1

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whatdoesmysitecost.com

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1GB for 10€

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1GB for 10€ 400 times 2.5MB

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1GB for 10€ 400 times 2.5MB 1 VISIT costs 0.025€

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1GB for 10€ 400 times 2.5MB 1 VISIT costs 0.025€ 1 MB costs 0.01€!!!

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httparchive.org/

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AVERAGE PAGE WEIGHT DESKTOP NOVEMBER 2010 702 KB SEPTEMBER 2017 3376 KB

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AVERAGE PAGE WEIGHT MOBILE JUNE 2011 377 KB SEPTEMBER 2017 2949 KB

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AVERAGE PAGE WEIGHT MOBILE JUNE 2011 377 KB SEPTEMBER 2017 2949 KB 0.03 €

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But it's not only about page weight...

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It's about user experience

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More weight doesn't mean more wait Scott Jehl filament group

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www.ﬁlamentgroup.com/lab/weight-wait.html 8 SECONDS FASTER PAINT WITHOUT REMOVING CONTENT

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DISTRACT THE USER

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Web Performance matters!

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Pinterest increased 15% SEO trafﬁc and 15% conversion rate to signup. BBC loses 10% of users for every additional second in load time. The Trainline reduced latency and customers spent an extra ~$11.5 million a year.

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Get your business use case! WPO stats wpostats.com

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But let's kick things off ctﬂ.io/fe-web-perf

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github.com/stefanjudis/webperf-101-workshop github.com/stefanjudis/webperf-101-workshop-ﬁnal

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- getting started - git clone [email protected]:stefanjudis/webperf-101-workshop.git npm i npm run dev git clone [email protected]:stefanjudis/webperf-101-workshop-final.git npm i npm run dev

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EXAMPLE SITE (BASED ON BOOTSTRAP) CHROME DESKTOP DSL CONNECTION

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EXAMPLE SITE (BASED ON BOOTSTRAP) IPHONE 6 3G CONNECTION

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- before vs after - www.webpagetest.org/video/compare.php?tests=171010_KV_c9dbe9afd5435e841acb6ee0f8b4342f, 171010_0S_90d4ae1819496d143a8342a76351ab23

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- before vs after - www.webpagetest.org/result/171010_1S_d994486799ea8416dcd982fd4139976d/ www.webpagetest.org/result/171010_1S_d994486799ea8416dcd982fd4139976d/

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Measure everything!

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WAYS TO MEASURE PERFORMANCE Synthetic Monitoring Real User Monitoring

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- Synthetic Monitoring - calibreapp.com/ speedcurve.com/

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- Synthetic Monitoring - www.sitespeed.io/

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developers.google.com/speed/pagespeed/insights/? url=https%3A%2F%2Fstefanjudis.github.io%2Fwebperf-101-workshop%2Fdist%2F

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- Synthetic Monitoring - www.webpagetest.org/result/171009_97_b14478acf4e583428d01a7b7bd202fbb/

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- Real User Monitoring - https://analytics.google.com mpulse.soasta.com/concerto/Central?anon=true

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www.perf-tooling.today/tools?q=metrics

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- Real User Monitoring -

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TOPICS 01 02 03 04 05 06 07 10 11 12 13 14 15 SCRIPT LOADING LAZY LOADING IMAGE FORMATS IMAGE COMPRESSION VIDEO TEXT COMPRESSION RESPONSIVE IMAGES FONT LOADING CONCAT & MINIFY CRITICAL PATH NEW METRICS PRE LOADING HTTP/2 08 ICONS 16 BUDGETING 09 CACHING 17 UNUSED CODE

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01 IMAGE FORMATS

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Images are 53% of the overall trafﬁc httparchive.org/interesting.php?a=All&l=Sep%201%202017

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TRADITIONAL IMAGE FORMATS GIF JPG PNG SVG

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Is it a vector graphic? YES NO

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Is it a vector graphic? SVG YES GIF PNG JPEG NO

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Need animation? YES NO YES NO YES NO developers.google.com/web/fundamentals/performance/optimizing-content-efﬁciency/image-optimization

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Need animation? GIF YES NO YES NO YES NO developers.google.com/web/fundamentals/performance/optimizing-content-efﬁciency/image-optimization

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Need animation? GIF Need to preserve ﬁne detail, with highest resolution or transparency? YES NO YES NO YES NO developers.google.com/web/fundamentals/performance/optimizing-content-efﬁciency/image-optimization

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Need animation? GIF Need to preserve ﬁne detail, with highest resolution or transparency? Need a large color palette? (+256 colors) YES NO YES NO YES NO developers.google.com/web/fundamentals/performance/optimizing-content-efﬁciency/image-optimization

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Need animation? GIF Need to preserve ﬁne detail, with highest resolution or transparency? Need a large color palette? (+256 colors) PNG-8 PNG-24 YES NO YES NO YES NO developers.google.com/web/fundamentals/performance/optimizing-content-efﬁciency/image-optimization

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Need animation? GIF Need to preserve ﬁne detail, with highest resolution or transparency? Need a large color palette? (+256 colors) PNG-8 PNG-24 JPEG YES NO YES NO YES NO developers.google.com/web/fundamentals/performance/optimizing-content-efﬁciency/image-optimization

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2000×1038

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gif – 1.4MB (0.01€)

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png-8 – 933KB (0.009€)

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png-24 – 3.2MB (0.03€)

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jpeg (Q65) – 399KB (0.004€)

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image formats “Are there alternatives?

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EXOTIC IMAGE FORMATS WEBP JPEG 2000 FLIF JPEG XR BPG

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EXOTIC IMAGE FORMATS WEBP JPEG 2000 FLIF JPEG XR No support No support BPG

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webp – 121KB (0.001€)

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progressive enhancement Some image

www.useragentman.com/blog/2015/01/14/using-webp-jpeg2000-jpegxr-apng-now-with-pictureﬁll-and-modernizr/

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server side detection RewriteEngine On # Check if browser support WebP images RewriteCond %{HTTP_ACCEPT} image/webp # Check if WebP replacement image exists RewriteCond %{DOCUMENT_ROOT}/$1.webp -f # Serve WebP image instead RewriteRule (.+)\.(jpe?g|png)$ $1.webp [T=image/webp,E=accept:1] Header append Vary Accept env=REDIRECT_accept AddType image/webp .webp images.guide/#-a-id-how-do-i-serve-webp-href-how-do-i-serve-webp-how-do-i-serve-webp-a- .htaccess

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server side detection .htaccess www.igvita.com/posts/12/xbandwidth-vs-latency.png.pagespeed.ic.rKtq8Mdb7q.jpg

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feature detection github.com/Modernizr/Modernizr/blob/ 5eea7e2a213edc9e83a47b6414d0250468d83471/feature-detects/img/webp.js

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CODING TIME

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02 IMAGE COMPRESSION

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- jpeg quality -

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- jpeg compression modes -

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calendar.perfplanet.com/2016/even-faster-images-using-http2-and-progressive-jpegs/

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JPEG ENCODER LIBJPEG MOZJPEG GUETZLI

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libjpeg – 399KB (0.004€)

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guetzli – 336KB (0.003€)

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mozjpeg – 197KB (0.002€)

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github.com/imagemin/imagemin-guetzli github.com/imagemin/imagemin-mozjpeg github.com/imagemin/imagemin

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github.com/JamieMason/ImageOptim-CLI imageoptim.com/mac

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CODING TIME

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The joy of optimizing by Una Kravets vimeo.com/190871719

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images.guide/

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03 RESPONSIVE IMAGES

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load images responsively How I learned to love JavaScript Or how I saved some bytes... How I learned to love JavaScript Desktop 21MB (0.21€) Mobile 30MB (0.30€)

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load images responsively Seattle Skyline

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load images responsively Seattle Skyline

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all jpeg ~170KB (0.002€)

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CODING TIME

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04 VIDEO

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Average video response size is 789KB httparchive.org/interesting.php?a=All&l=Sep%2015%202017

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# $ compress_video caniuse.mp4 caniuse_compressed.mp4 function compress_video() { if ! [ $# -eq 2 ]; then echo "Wrong parameter usage: \n $ compress_video " return 1 fi ffmpeg -i $1 -vcodec h264 -b:v 1000k -acodec mp2 $2 } compress video on the ﬂy

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mp4 vs. webm

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progressive enhancement

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5.2M share-inbox.mp4 (0.05€) 1.1M share-inbox_web.mp4 (0.01€) 515K share-inbox_web.webm (0.005€) compression

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# $ prepare_video caniuse.mp4 caniuse_compressed function prepare_video() { if ! [ $# -eq 1 ]; then echo "Wrong parameter usage: \n $ compress_video " return 1 fi ffmpeg -i $1 -vcodec h264 -b:v 1000k -acodec mp2 $2.mp4 ffmpeg -i $2.mp4 -strict -2 $2.webm } compress video on the ﬂy github.com/stefanjudis/.dotﬁles/blob/master/functions.zsh#L61-L69

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Use video responsibly

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www.webpagetest.org/video/view.php?id=150209_e46843cf0dc768ccc6641e944d3551d05175dd9f use video responsibly

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05 TEXT COMPRESSION

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twitter.com/dougsillars/status/917464153522102272

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gzip AddOutputFilterByType DEFLATE application/javascript AddOutputFilterByType DEFLATE application/xml AddOutputFilterByType DEFLATE image/svg+xml AddOutputFilterByType DEFLATE text/css AddOutputFilterByType DEFLATE text/html AddOutputFilterByType DEFLATE text/javascript AddOutputFilterByType DEFLATE text/plain AddOutputFilterByType DEFLATE text/xml ... ... ... .htaccess

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2.4M application-97681b5991.min.js (0.02€) 708K application-97681b5991.min.js.gz (0.007€) gzip .htaccess

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accept-encoding: gzip, deflate, br

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brotli 2.4M application-97681b5991.min.js (0.02€) 708K application-97681b5991.min.js.gz (0.007€) 526K application-97681b5991.min.js.br (0.005€) samsaffron.com/archive/2016/06/15/the-current-state-of-brotli-compression brotli css-tricks.com/brotli-static-compression/

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brotli caniuse.com/#feat=brotli

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06 CACHING

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jakearchibald.com/2016/caching-best-practices/

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cache-control: max-age=31556926 caching of static assets www.stefanjudis.com/_nuxt/pages/index.3b10328682a1efde514e.js https://images.contentful.com/f20lfrunubsq/qZrrGql6VwaoE2YU8CUuE/ a4276082432402bd90933ab3de335bf7/stock-photo-227882431.jpg?w=300 cache-control: max-age=590039 ~1 YEAR ~1 WEEK

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caching of static assets https://www.facebook.com/rsrc.php/v3/yD/r/FLAXZ9xHT18.js ~1 YEAR cache-control: max-age=31536000,immutable

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caching of static assets

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caching of static assets

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caching of static assets “When you reload, browsers revalidate the page that you are currently on, even if that page hasn't expired yet. However, they also go a step further and revalidate all sub-resources on the page — things like images and JavaScript ﬁles.

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code.facebook.com/posts/557147474482256/this-browser-tweak-saved-60-of-requests-to-facebook/

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hacks.mozilla.org/2017/01/using-immutable-caching-to-speed-up-the-web/

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- immutable - developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#Browser_compatibility cache-control: public,max-age=31536000,immutable

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07 CONCAT & MINIFY

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github.com/mishoo/UglifyJS

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github.com/jakubpawlowicz/clean-css

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github.com/kangax/html-miniﬁer

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CODING TIME

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08 ICONS

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ICON FONTS

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cloudfour.com/thinks/seriously-dont-use-icon-fonts/

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Using SVGs

load as img ... inline SVG .element { background-image: url(/images/image.svg); } load SVG in CSS

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Using SVGs Basketball load as an icon system

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www.perf-tooling.today/tools

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https://github.com/svg/svgo jakearchibald.github.io/svgomg/

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CODING TIME

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09 SCRIPT LOADING

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script loading “Put scripts at the end of the ﬁle, right?

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script loading vs vs

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script loading HTML parsing

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script loading HTML parsing HTML parsing paused HTML parsing Script fetch Script execution

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script loading HTML parsing async

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script loading HTML parsing HTML parsing Script fetch Script execution async

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script loading HTML parsing defer

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script loading HTML parsing Script fetch Script execution defer

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script loading HTML parsing fetch async vs. defer async defer fetch HTML parsing fetch fetch 1 2

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script loading HTML parsing fetch async vs. defer async defer fetch execution execution HTML parsing fetch fetch execution execution 1 2

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bitsofco.de/async-vs-defer/

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script loading “Which one do you prefer?

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calendar.perfplanet.com/2016/prefer-defer-over-async/

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SPOF

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Without blocking script With blackboxed script

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chrome.google.com/webstore/detail/spof-o-matic/plikhggfbplemddobondkeogomgoodeg

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TRUST

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“What's the ROI of your 3rd parties? 3rd parties

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requestmap.webperf.tools/render/171008_D7_e0fbc654e0da0b7b97b1c0f53964f7d2

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REMOVE, REMOVE, ...

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3rd parties

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www.webpagetest.org/result/171009_CV_a6df9efc6f6861175a3963b22d1f1103/1/details/#waterfall_view_step1

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twitter.com/DasSurma/status/915573188398022656

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CODING TIME

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10 CRITICAL PATH

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critical path “ Get something on the screen as soon as possible

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http connection “What's needed to establish an HTTP connection?

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http connection DNS lookup initial connection TCP SSL/TLS negotiation TTFB content download

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hpbn.co/building-blocks-of-tcp/ Roundtrip time 56ms

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latency on mobile (3g connection) de.slideshare.net/metrofun/reduce-mobile-latency Control plane latency Internet routing latency Internal latency (CDNs, ISPs, Caches, Proxies) (Firewalls, Load Balancers, Servers) ~600ms ~200ms

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www.igvita.com/2012/07/19/latency-the-new-web-performance-bottleneck/ latency matters

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latency matters

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inline critical CSS index.html main.css

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inline critical CSS index.html start render main.css

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inline critical CSS index.html (inline CSS) main.css

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inline critical CSS start render index.html (inline CSS) main.css

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github.com/ﬁlamentgroup/loadCSS

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inline critical CSS // critical styles /*! loadCSS. [c]2017 Filament Group, Inc. MIT License */ (function(){ ... }()); /*! loadCSS rel=preload polyfill. [c]2017 Filament Group, Inc. MIT License */ (function(){ ... }());

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github.com/addyosmani/critical

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speakerdeck.com/patrickhamann/css-and-the-ﬁrst-meaningful-paint-css-conf-eu-may-2017

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11 UNUSED CODE

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github.com/giakki/uncss

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ANALYSE PACKAGES

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github.com/twbs/bootstrap/blob/v4-dev/scss/bootstrap.scss

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CODING TIME

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12 LAZY LOADING

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lazy loading “How do you  implement lazy loading?

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function isElementInViewport (el) { var rect = el.getBoundingClientRect(); return ( rect.top >= 0 && rect.left >= 0 && rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) && rect.right <= (window.innerWidth || document.documentElement.clientWidth) ); } How to tell if a DOM element is visible in the current viewport? stackoverﬂow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport

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function isElementInViewport (el) { var rect = el.getBoundingClientRect(); // can trigger force layout/reflow return ( rect.top >= 0 && rect.left >= 0 && rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) && rect.right <= (window.innerWidth || document.documentElement.clientWidth) ); } How to tell if a DOM element is visible in the current viewport? stackoverﬂow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport

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WHAT FORCES LAYOUT / REFLOW gist.github.com/paulirish/5d52fb081b3570c81e3a

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Implementation with 'scroll' const speakers = [...document.querySelectorAll('.lazy')]; window.addEventListener('scroll', () => { speakers.forEach(elem => { if (isElementInViewport(elem)) { // load image } }); });

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Implementation with 'scroll' const speakers = [...document.querySelectorAll('.lazy')]; window.addEventListener('scroll', () => { // really expensive speakers.forEach(elem => { if (isElementInViewport(elem)) { // load image } }); });

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Implementation with 'scroll' 60FPS 1s / 60 16ms

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Implementation with 'scroll' 60FPS 1s / 60 10ms 16ms

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Intersection Observer

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- Intersection Observer - (function() { const options = { threshold: 1.0 }; const intersectionObserver = new IntersectionObserver((entries) => { entries.forEach((entry) => { if (entry.isIntersecting) { // load image } }); }, options); [...document.querySelectorAll('.lazy')] .forEach(elem => intersectionObserver.observe(elem)); })();

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- Intersection Observer - caniuse.com/#feat=intersectionobserver * in development *

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github.com/w3c/IntersectionObserver/tree/master/polyﬁll

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github.com/ApoorvSaxena/lozad.js

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CODING TIME

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13 PRE LOADING

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rel="preconnect" rel="dns-prefetch" rel="preload" rel="prefetch" www.w3.org/TR/resource-hints/#dns-prefetch-link-relation-type www.w3.org/TR/resource-hints/#preconnect-link-relation-type www.w3.org/TR/resource-hints/#prefetch-link-relation-type www.w3.org/TR/preload/

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Preload resources you have high- conﬁdence will be used in the current page. Prefetch resources likely to be used for future navigations across multiple navigation boundaries. “

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www.smashingmagazine.com/2016/02/preload-what-is-it-good-for/

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medium.com/reloading/preload-prefetch-and-priorities-in-chrome-776165961bbf

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www.stefanjudis.com

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- rel="dns-prefetch" - caniuse.com/#feat=link-rel-dns-prefetch

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- rel="preconnect" - caniuse.com/#feat=link-rel-preconnect

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- rel="preload" - caniuse.com/#feat=link-rel-preload

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- rel="prefetch" - caniuse.com/#feat=link-rel-prefetch

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Link: ; rel=dns-prefetch Link: ; rel=preconnect Link: ; rel=prefetch; Link: ; rel=preload; as=image; Usage link element header

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medium.com/@benschwarz/the-critical-request-90bb47da5769

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CODING TIME

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15 FONT LOADING

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- font loading behavior - FOUT? FOIT?

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- font loading behavior - FOUT FOIT www.bramstein.com/writing/web-font-loading-patterns.html

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- font loading behavior -

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FOIT! - font loading behavior -

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- font loading behavior - FOUT FOIT FOIT FOIT FOIT 3s 3s 3s 3s - www.zachleat.com/web/fout-foit-history/

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body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; } github.com

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css-tricks.com/snippets/css/system-font-stack/

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FONTS ON MOBILE?

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@media screen and (min-width: 52em) { body { font-family: 'Droid Sans', sans-serif; } } no fonts for mobile?

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- font rendering controls - font-display: auto; font-display: block; font-display: swap; font-display: fallback; font-display: optional; developer.mozilla.org/en-US/docs/Web/CSS/@font-face/font-display

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- font rendering controls - caniuse.com/#feat=css-font-rendering-controls * * behind a ﬂag

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- preload fonts - Link: ; rel=preload; as=font;

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www.zachleat.com/web/comprehensive-webfonts/

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16 NEW METRICS

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new metrics “ What metrics do we have today?

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REAL USER METRICS (RUM) NAVIGATION TIMING API RESOURCE TIMING API USER TIMING API

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- Navigation Timing API - w3c.github.io/navigation-timing/ window.performance.timing

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- Navigation Timing API - { "navigationStart": 1494722965671, "unloadEventStart": 0, "unloadEventEnd": 0, "redirectStart": 0, "redirectEnd": 0, "fetchStart": 1494722965838, "domainLookupStart": 1494722965841, "domainLookupEnd": 1494722972627, "connectStart": 1494722972627, "connectEnd": 1494722973191, "secureConnectionStart": 1494722972815, "requestStart": 1494722973191, "responseStart": 1494722973667, "responseEnd": 1494722973681, "domLoading": 1494722973681, "domInteractive": 1494722974288, "domContentLoadedEventStart": 1494722974288, "domContentLoadedEventEnd": 1494722974320, "domComplete": 1494722974571, "loadEventStart": 1494722974571, "loadEventEnd": 1494722974574 } w3c.github.io/navigation-timing/ window.performance.timing

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- Navigation Timing API - w3c.github.io/navigation-timing/

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- Resource Timing API - window.performance.getEntriesByType('resource')

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- Resource Timing API - [ ..., { connectEnd: 117.69500000000001, connectStart: 117.69500000000001, decodedBodySize: 20133, domainLookupEnd: 117.69500000000001, domainLookupStart: 117.69500000000001, duration: 846.3100000000001, encodedBodySize: 20133, entryType: 'resource', fetchStart: 117.69500000000001, initiatorType: 'img', name: 'http://127.0.0.1:8080/image.png', redirectEnd: 0, redirectStart: 0, requestStart: 962.6750000000001, responseEnd: 964.0050000000001, responseStart: 963.45, secureConnectionStart: 0, startTime: 117.69500000000001, transferSize: 20391, workerStart: 0 } ] www.w3.org/TR/resource-timing-1/ window.performance.getEntriesByType('resource')

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[...Array(20)].forEach(cornify_add); - User Timing API - w3c.github.io/user-timing/ if (talksSeen === nrOfTalks) { }

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- User Timing API - w3c.github.io/user-timing/ if (talksSeen === nrOfTalks) { // measure how long this takes performance.mark('cornify_start'); [...Array(20)].forEach(cornify_add); performance.mark('cornify_end'); performance.measure( 'cornify_processing_time', 'cornify_start', 'cornify_end' ); }

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- User Timing API - w3c.github.io/user-timing/ window.performance.getEntriesByType('mark') [ { duration: 0 entryType: 'mark' name: 'cornify_start' startTime: 39613.885 }, ... ]

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- User Timing API - w3c.github.io/user-timing/ window.performance.getEntriesByType('measure') [ { duration: 5.9900000000016 entryType: 'measure' name: 'cornify_processing_time' startTime: 46002.34500000001 }, ... ]

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ENTRY TYPE VALUES mark measure navigation resource ACCESSIBLE VIA getEntries getEntriesByType getEntriesByName

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GOOD METRICS

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- Speed Index -

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- Speed Index -

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performance.clearMarks("img displayed"); performance.mark("img displayed"); speedcurve.com/blog/user-timing-and-custom-metrics/ - custom metrics -

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- paint timing - www.w3.org/TR/paint-timing/ const perfObserver = new PerformanceObserver(list => { list.getEntries().forEach((entry) => { // Process entries // report back for analytics and monitoring // entry.name -> 'first-paint' // entry.name -> 'first-contentful-paint' } ); }); perfObserver.observe({entryTypes: ['paint']}); window.performance.getEntriesByType('paint')

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github.com/w3c/longtasks var perfObserver = new PerformanceObserver(function(list) { list.getEntries().forEach((entry) => { // Process entries // report back for analytics and monitoring // ... }); }); perfObserver.observe({entryTypes: ['longtask']}); - longtask - window.performance.getEntriesByType('longtask')

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- Performance Observer - developer.mozilla.org/en-US/docs/Web/API/PerformanceObserver * * behind a ﬂag

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No content

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LEVERAGING THE METRICS THAT MOST AFFECT USER EXPERIENCE https://www.youtube.com/watch?v=6Ljq-Jn-EgU

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www.sitepen.com/blog/2017/10/06/improving-performance-with-the-paint-timing-api/

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17 HTTP/2

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www.httpvshttps.com/

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www.httpvshttps.com/

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www.webpagetest.org/result/171008_AF_e0b47ffc2e10a439dc8fb25aecf6d8b4/

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www.webpagetest.org/result/171008_JA_c36bf495a6399f112b3c5eadb095190c/

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- Header Compression - blog.cloudﬂare.com/hpack-the-silent-killer-feature-of-http-2/

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PUSH?

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blogs.akamai.com/2017/03/http2-server-push-the-what-how-and-why.html

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jakearchibald.com/2017/h2-push-tougher-than-i-thought/

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The perfect preload will always be slightly slower than the perfect HTTP/2 push, since it doesn't need to wait for the browser to make the request. However, preloading is drastically simpler and easier to debug. I recommend using it today, as browser support is only going to get better – but do keep an eye on devtools to ensure your pushed items are being used. “

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tools.ietf.org/html/draft-ietf-httpbis-cache-digest-00

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HTTP/1.x vs HTTP/2 “Should you turn it on today?

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HTTP/1.x vs HTTP/2 “Hell yeah!

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HTTP/1.x vs HTTP/2 HTTP/1.x HTTP/2 DOMAIN SHARDING CONCAT FILES INLINE RESOURCES ? ? ?

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HTTP/1.x vs HTTP/2 HTTP/1.x HTTP/2 DOMAIN SHARDING CONCAT FILES INLINE RESOURCES DOMAIN SHARDING CONCAT FILES INLINE RESOURCES * * * always measure

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engineering.khanacademy.org/posts/js-packaging-http2.htm

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ALWAYS MEASURE!

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hpbn.co/

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18 BUDGETING

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timkadlec.com/2013/01/setting-a-performance-budget/

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BIZ HAS TO BE ON BOARD

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www.webpagetest.org/video/compare.php? tests=171009_2S_68d930ae2b145ca338a70b97c93fbf19,171009_28_74873eb32a55 a5eb963d65c0d2253951

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github.com/addyosmani/psi developers.google.com/speed/pagespeed/insights/

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github.com/marcelduran/webpagetest-api www.webpagetest.org/

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github.com/GoogleChrome/lighthouse developers.google.com/web/tools/lighthouse/

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- performance budget - “ What is a good budget?

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- performance budget - 600 KB total page weight 01 20 requests 02 03 1000 Speed Index 04 1s start render time 05 Start render 3-4s on 3g ...

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- performance budget - “You decide!

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What happens if something does not ﬁt within the budget? Steve Souders Speedcurve Optimize? Remove? Don't do it?