Improving Performance with Responsive Images [NAGW]

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1 Improving Performance with Responsive Images David Newton | St. Michael’s Hospital

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2 2 https://github.com/nwtn/pres-respimg-perf-nagw

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3 “Good performance is good design” —Brad Frost

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Responsive Web Design 4

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10 63% of Americans used a phone to access the internet ! 34% of Americans used a mobile device as their primary way to access the web

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11 “More human beings today have access to a cellphone than…a clean toilet.” Anand Giridharadas, New York Times, April 10 2010

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12 “More human beings today have access to a cellphone than…a clean toilet.” Anand Giridharadas, New York Times, April 10 2010

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17 1. A flexible, grid-based layout, 2. Flexible images and media, 3. Media queries, a module from the CSS3 specification

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18 1. A flexible, grid-based layout, 2. Flexible images and media, 3. Media queries, a module from the CSS3 specification

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Responsive Images 19

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20 img { max-width: 100%; }

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23 A solution:   Serve one big image and let the browser scale it

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Performance 27

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28 Average web page size: 1,860 KB    Images account for: 1,180 KB (>63%)    HTTP Archive, September 1 2014

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30 2x resolution = 4x as many pixels ! 3x resolution = 9x as many pixels ! 4x resolution = 16x as many pixels

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31 energy more pixels = more money time

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32 —Dave Rupert

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33 “Good performance is good design” —Brad Frost

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34 A solution:   Serve one big image and let the browser scale it

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35 A better solution:   Serve an appropriate image to each user

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Responsive Images 36 (Again)

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40 SVG WebP JPEG XR

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42 + srcset + sizes    http://whatwg.org/html#the-picture-element

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43 Using CSS is a bad idea.

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44 Using JavaScript is a bad idea.

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45 + srcset + sizes    http://whatwg.org/html#the-picture-element

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46 Firefox (Gecko) srcset (partial) N/A srcset (full) + sizes behind a flag: FF33 on by default: FF34? picture behind a flag: FF33 on by default: FF34?

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47 Firefox (Gecko) Chrome/Opera (Blink) srcset (partial) N/A Chrome 34 srcset (full) + sizes behind a flag: FF33 on by default: FF34? behind a flag: Chrome 37 on by default: Chrome 38 picture behind a flag: FF33 on by default: FF34? behind a flag: Chrome 37 on by default: Chrome 38

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48 Firefox (Gecko) Chrome/Opera (Blink) Safari (WebKit) srcset (partial) N/A Chrome 34 Safari 8 srcset (full) + sizes behind a flag: FF33 on by default: FF34? behind a flag: Chrome 37 on by default: Chrome 38 Safari 8.1? picture behind a flag: FF33 on by default: FF34? behind a flag: Chrome 37 on by default: Chrome 38 Safari 8.1?

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49 Firefox (Gecko) Chrome/Opera (Blink) Safari (WebKit) IE (Trident) srcset (partial) N/A Chrome 34 Safari 8 12? srcset (full) + sizes behind a flag: FF33 on by default: FF34? behind a flag: Chrome 37 on by default: Chrome 38 Safari 8.1? 12? picture behind a flag: FF33 on by default: FF34? behind a flag: Chrome 37 on by default: Chrome 38 Safari 8.1? 12?

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50 Picturefill by Scott Jehl ! https://github.com/scottjehl/picturefill

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Markup 51

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Markup 52 Device Pixel Ratio-Switching

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Markup 59 Viewport- and screen resolution-switching

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NO!

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Markup 74 File type-switching

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Markup 83 Art direction

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Markup 95 All the things!

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Markup 96 All the things! a.k.a. the scary slide

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99 http://whatwg.org/html#the-picture-element

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100 A better solution:   Serve an appropriate image to each user

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1 Improving Performance with Responsive Images David Newton | St. Michael’s Hospital

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1 Improving Performance with Responsive Images David Newton | St. Michael’s Hospital RESPONSIBLE!

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1. Responsive images 2. 3. 4. 5. 6. 103

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104 1. Responsive images 2. Image optimization 3. 4. 5. 6.

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105 ImageOptim  https://imageoptim.com/ ! ImageOptim-CLI http://jamiemason.github.io/ImageOptim-CLI/ ! Scour https://launchpad.net/scour ! grunt-svgmin https://github.com/sindresorhus/grunt-svgmin

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106 SetOutputFilter DEFLATE AddOutputFilterByType DEFLATE "image/svg+xml" ! ! Note: Apache is confusing and I’m not guaranteeing this will work.

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107 1. Responsive images 2. Image optimization 3. 4. 5. 6.

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108 1. Responsive images 2. Image optimization 3. Deferred image loading 4. 5. 6.

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111 Resource Priorities http://www.w3.org/TR/resource-priorities/ ! Preloading and deferred loading of scripts and other resources http://lists.whatwg.org/htdig.cgi/whatwg- whatwg.org/2014-August/297533.html

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112 LazyLoad JS scripts and plugins, e.g.: ! http://css-tricks.com/snippets/javascript/lazy- loading-images/

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113 1. Responsive images 2. Image optimization 3. Deferred image loading 4. 5. 6.

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114 1. Responsive images 2. Image optimization 3. Deferred image loading 4. Caching 5. 6.

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115 ExpiresActive on ExpiresDefault "access plus 1 month" ExpiresByType image/gif "access plus 1 year" ExpiresByType image/jpeg "access plus 1 year" ExpiresByType image/png "access plus 1 year" ExpiresByType image/svg+xml "access plus 1 year" ! Note: Apache is confusing and I’m not guaranteeing this will work.

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116 1. Responsive images 2. Image optimization 3. Deferred image loading 4. Caching 5. 6.

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117 1. Responsive images 2. Image optimization 3. Deferred image loading 4. Caching 5. CDNs 6.

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118 1. Responsive images 2. Image optimization 3. Deferred image loading 4. Caching 5. CDNs 6. Fewer images

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120 1. Responsive images 2. Image optimization 3. Deferred image loading 4. Caching 5. CDNs 6. Fewer images

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Impact 121

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124 HTML 2 KB Scripts 29 KB CSS 1 KB Images 661 KB Total: 693 KB

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125 Unoptimized (Firefox) Unoptimized (Safari/iOS) Load time 2.2s 2.1s

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▪ Responsive images #1: use srcset and sizes to serve images at an appropriate size  ▪ Responsive images #2: use picture, source, and type to serve SVG and WebP versions where possible  ▪ Optimization: progressive encoding; use ImageOptim and Scour to optimize file size; serve SVGs gzipped  ▪ Deferred image loading: use a modified lazyload.js to defer loading of images that are below the fold 126

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127 2 KB 29 KB 1 KB Images 661 KB Total: 693KB

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128 HTML 3 KB Scripts 33 KB CSS 1 KB Images 253 KB Total: 290KB (~58% savings) 2 KB 29 KB 1 KB Images 661 KB Total: 693KB

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129 HTML 3 KB Scripts 33 KB CSS 1 KB Images 87 KB Total: 119 KB (~83% savings) 2 KB 29 KB 1 KB Images 661 KB Total: 693 KB

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130 Unoptimized (Firefox/Desktop) Optimized (Firefox/Desktop) Unoptimized (Safari/iOS) Optimized (Safari/iOS) Load time 2.2s 2.0s 2.1s 1.7s

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132 “Good performance is good design” —Brad Frost

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133 “Responsible images are good design” —Dave Newton

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134 Dave Newton   Twitter: @newtron GitHub: @nwtn Email: david@davidnewton.ca    Slides, links, image credits, and more:  https://github.com/nwtn/pres-respimg-perf-nagw