Slide 1
Slide 1 text
Instant
Loading
Making the web competitive
on mobile
PayPal, Oct 17’
@addyosmani
Slide 2
Slide 2 text
My desk
Slide 3
Slide 3 text
Improving performance is a journey. Lots of
small changes can lead to big gains.
Slide 4
Slide 4 text
1. JavaScript Frameworks
2. Large JavaScript Bundles
3. PRPL Pattern
4.
5.
6. Reduction in HTTP Requests
7. Service Workers
8. Image Compression
TOPICS
Slide 5
Slide 5 text
loading is a user journey
with many disparate expectations
you’ve probably heard to REDUCE DNS LOOKUPS, REDUCE ROUND-TRIP TIMES, MINIMIZE REDIRECTS, ELIMINATE UNN
Slide 6
Slide 6 text
No content
Slide 7
Slide 7 text
USERS LOOK FOR VISUAL FEEDBACK TO reassure
them everything is working as expected.
Slide 8
Slide 8 text
first Interactive
consistently Interactive
Slide 9
Slide 9 text
Time to Interactive
<5s
on an average mobile
device over 3G
*2s on repeat-load a:er Service Worker registered
GOAL
Slide 10
Slide 10 text
19s
16s 420KB
JavaScript Startup Performance, Double-Click Mobile Speed Matters report & the HTTP Archive
The average web page on mobile in 2017
UNTIL INTERACTIVE FULLY LOADED JAVASCRIPT
Slide 11
Slide 11 text
No content
Slide 12
Slide 12 text
No content
Slide 13
Slide 13 text
No content
Slide 14
Slide 14 text
PERFORMANCE
JavaScript
Start-up Start-up
o o
V8 Runtime Call Stats
Slide 15
Slide 15 text
1MB script
(250KB minified)
JS Parse Time On Mobile
Slide 16
Slide 16 text
No content
Slide 17
Slide 17 text
about:inspect in Chrome DevTools
Slide 18
Slide 18 text
No content
Slide 19
Slide 19 text
No content
Slide 20
Slide 20 text
No content
Slide 21
Slide 21 text
Apple A11 Arm64 SOC in iPhone8 benchmarks faster than x86 in Macbook Pro
Slide 22
Slide 22 text
webpagetest.org/easy
Moto G4 + 3G
Slide 23
Slide 23 text
A closer look at PayPal.com
Slide 24
Slide 24 text
No content
Slide 25
Slide 25 text
Opportunities to dns-prefetch more?
Slide 26
Slide 26 text
resources
for the next navigation
Slide 27
Slide 27 text
Authenticated PayPal.com
Slide 28
Slide 28 text
Ideally, test on real (average)
mobile hardware.
CPU, GPU, cores, network packet loss
can all introduce variance.
Slide 29
Slide 29 text
16 seconds in before
First Paint
Slide 30
Slide 30 text
20 seconds before we see
First Meaningful Paint
Slide 31
Slide 31 text
30 seconds before the page
is Continuously Interactive
Slide 32
Slide 32 text
Network bound for 3+ seconds
Slide 33
Slide 33 text
14s just fetching resources
Slide 34
Slide 34 text
11 seconds in idle time (time when the
browser is waiting on the CPU or GPU to
do some processing)
Slide 35
Slide 35 text
~6 seconds spent just in parsing & compiling
JavaScript
Party on the main
thread
Slide 36
Slide 36 text
No content
Slide 37
Slide 37 text
By default, React includes many helpful warnings.
These warnings are very useful in development.
However, they make React larger and slower so you
should make sure to use the production version
when you deploy the app.
Slide 38
Slide 38 text
No content
Slide 39
Slide 39 text
50% of script
immediately
loaded is unused
Slide 40
Slide 40 text
Use babel-preset-env to only transpile code for browsers that need it
{
"presets": [
["env", {
"targets": {
"browsers": ["last 2 versions"]
}
}]
]
}
Only transpile what you need with
Slide 41
Slide 41 text
Many sites optimize for the Lowest Common Denominator
Most users end up being deployed ES2015 polyfills
Slide 42
Slide 42 text
Deploying ES2015+ JavaScript in 2017
babel-preset-env +
Slide 43
Slide 43 text
Deploying ES2015+ JavaScript in 2017
main-legacy.js main.js
Slide 44
Slide 44 text
Switching to MozJPEG
could save 60% on bytes
Slide 45
Slide 45 text
No content
Slide 46
Slide 46 text
Continuous
Performance
Tracking
Slide 47
Slide 47 text
No content
Slide 48
Slide 48 text
Code-splitting
// Defines a “split-point” for a separate bundle
require.ensure([], () => {
const profile = require('./UserProfile', cb);
});
import('./UserProfile')
.then(loadRoute(cb))
.catch(errorLoading)
Webpack 2+
Webpack 1
Also see Splittable, Closure Compiler
or Browserify
Slide 49
Slide 49 text
Minify _everything_
Babelified ES5 w/Uglify
ES2015+ with Babili
css-loader + minimize:true
Code-splitting
Dynamic import()
Route-based chunking
Tree-shaking
Webpack 2+ with Uglify
RollUp
DCE w/ Closure Compiler
Optimize “Vendor” libs
NODE_ENV=production
CommonsChunk + HashedModuleIdsPlugin()
Transpile less code
babel-preset-env + modules:false
Browserlist
useBuiltIns: true
Scope Hoisting:
Webpack 3
RollUp
Strip unused Lodash modules
lodash-webpack-plugin
babel-plugin-lodash
Fewer Moment.js locales
ContextReplacementPlugin()
Slide 50
Slide 50 text
workflow
Slide 51
Slide 51 text
No content
Slide 52
Slide 52 text
No content
Slide 53
Slide 53 text
No content
Slide 54
Slide 54 text
No content
Slide 55
Slide 55 text
No content
Slide 56
Slide 56 text
No content
Slide 57
Slide 57 text
No content
Slide 58
Slide 58 text
No content
Slide 59
Slide 59 text
No content
Slide 60
Slide 60 text
No content
Slide 61
Slide 61 text
No content
Slide 62
Slide 62 text
No content
Slide 63
Slide 63 text
No content
Slide 64
Slide 64 text
No content
Slide 65
Slide 65 text
Webpack support for Pure Modules
Slide 66
Slide 66 text
No content
Slide 67
Slide 67 text
No content
Slide 68
Slide 68 text
Plenty of lightweight options for mobile
Lower total cost on size + parse times from the get-go
Slide 69
Slide 69 text
Preact on Lyft
Slide 70
Slide 70 text
Preact on Uber
Slide 71
Slide 71 text
No content
Slide 72
Slide 72 text
No content
Slide 73
Slide 73 text
No content
Slide 74
Slide 74 text
No content
Slide 75
Slide 75 text
Byte savings @
Slide 76
Slide 76 text
Brotli
Display Ads from Google now served
using Brotli compression!
40%
Data-savings up to
15% in aggregate over gzip
https://developers.googleblog.com/
Slide 77
Slide 77 text
Brotli
Improved load time by 7% in India & 4% U.S
bit.ly/linkedin-brotli
Decreased the size of static assets by 20%
bit.ly/dropbox-brotli
17% improvement for largest JS bundles
bit.ly/certsimple-brotli
1.5 petabytes (million gigs) saved a day
bit.ly/playstore-brotli
Slide 78
Slide 78 text
WebP
30% smaller than JPEG
25% smaller than PNG
Slide 79
Slide 79 text
WebP
bit.ly/webp-format
Serving over 43B image requests a day
25-30%
savings for WebP on average (26% lossless)
Data Saver + Web Store
Slide 80
Slide 80 text
WebP Conversion
XNConvert
Windows/Mac/Linux
Can convert in batch
Supports most formats
Alternatively:
imagemin
Pixelmator
ImageMagick
GIMP
Leptonica
Slide 81
Slide 81 text
WebP Serving
![]()
Or use the Accept header + .htaccess to serve WebP if a browser supports it and it exists on disk.
Slide 82
Slide 82 text
Service Workers
Inbox by Gmail
10%
improvement in Time-to-Interactive
Slide 83
Slide 83 text
No content
Slide 84
Slide 84 text
HTTP Caching Checklist
Use consistent URLs and minimize resource churn
Provide a validation token (ETag) to avoid transferring unchanged bytes
Identify resources that can be cached by intermediaries (like CDNs)
Determine the optimal cache lifetime of resources (max-age)
Consider a Service Worker for more control over your repeat visit caching
1.
2.
3.
4.
5.
bit.ly/caching-checklist
Slide 85
Slide 85 text
No content
Slide 86
Slide 86 text
Let’s hack
Slide 87
Slide 87 text
ResourceLoadPriorityVeryHigh
Slide 88
Slide 88 text
No content
Slide 89
Slide 89 text
No content
Slide 90
Slide 90 text
ResourceLoadPriorityVeryHigh
Slide 91
Slide 91 text
PayPal-inium
Slide 92
Slide 92 text
Original
Everything is high priority
Preloaded JS
Preloaded CSS + fonts
Slide 93
Slide 93 text
Original
Everything is high priority
JS + CSS is high priority
CSS + fonts are high prio
Slide 94
Slide 94 text
No content
Slide 95
Slide 95 text
No content
Slide 96
Slide 96 text
No content
Slide 97
Slide 97 text
No content
Slide 98
Slide 98 text
No content
Slide 99
Slide 99 text
..
Link: 1.js; rel="preload"; as="script"
Slide 100
Slide 100 text
No content
Slide 101
Slide 101 text
No content
Slide 102
Slide 102 text
No content
Slide 103
Slide 103 text
No content
Slide 104
Slide 104 text
bit.ly/prpl-paFern
PRPL
bit.ly/prpl-paFern
Slide 105
Slide 105 text
HTTP/2 with 3G
Slide 106
Slide 106 text
HTTP/2 + preload with 3G
Slide 107
Slide 107 text
No content
Slide 108
Slide 108 text
No content
Slide 109
Slide 109 text
Express + HTTP/2 Push Headers
const express = require('express'),
let app = express();
app
.use('/js', express.static('js'))
.get('/', function (req, res) {
res.set('Link', `
; rel=preload; as='style',
; rel=preload; as='script',
; rel=preload; as='script'`)
Slide 110
Slide 110 text
No content
Slide 111
Slide 111 text
No content
Slide 112
Slide 112 text
No content
Slide 113
Slide 113 text
Alternatively: Track cache content using cookies
if (supports_http2() && !http_cached('/app.js')) {
header('link:; rel=preload; as=script’);
setcookie('/app.js', 'is-cached', 0, '/');
}
Slide 114
Slide 114 text
Alternatively: Track cache content using cookies
function http_cached($filename) {
if ('is-cached' === $_COOKIE[$filename]) {
return true;
} else {
return false;
}
}
Try CASPer
Slide 115
Slide 115 text
No content
Slide 116
Slide 116 text
Repeat visit with Service Worker
Slide 117
Slide 117 text
Next: Differential Serving based on
browser compatibility?
HTTP/1 works better when resources are concatenated (bundled)
HTTP/2 works better when resources are more granular (unbundled)
Serve an unbundled build for server/browser combinations supporting
HTTP/2. Trigger delivery with or HTTP/2 Push
Serve a bundled build to minimize round-trips to get the app running on
server/browser combinations that don't support HTTP/2 Push
Slide 118
Slide 118 text
Debugging: HTTP/2 Server Push in DevTools
Slide 119
Slide 119 text
Debugging: HTTP/2 Server Push in DevTools
Slide 120
Slide 120 text
HTTP/2 Server Push Rules Of Thumb
Push just enough resources to fill idle network time, and no more.
Push resources in evaluation-dependence order.
Consider using strategies to track the client-side cache.
Use the right cookies when pushing resources.
Use server push to fill the initial cwnd. Consider
preload links to reveal remaining critical resources.
1.
2.
3.
4.
5.
bit.ly/h2push
PUSH
Slide 121
Slide 121 text
No content
Slide 122
Slide 122 text
PRPL In-A-Box
Polymer App
Toolbox
PREACT
CLI
Slide 123
Slide 123 text
No content
Slide 124
Slide 124 text
No content
Slide 125
Slide 125 text
No content
Slide 126
Slide 126 text
With Service Workers
Slide 127
Slide 127 text
With HTTP/2 Server Push
Slide 128
Slide 128 text
babel-preset-env + per-browser bundles
Slide 129
Slide 129 text
babel-preset-env + per-browser bundles
Slide 130
Slide 130 text
Twitter Lite
Slide 131
Slide 131 text
No content
Slide 132
Slide 132 text
Interactive in <5s on 3G
Slide 133
Slide 133 text
Can we get fast 3G numbers
across the board or regular
3G?
Slide 134
Slide 134 text
PRPL
Push / Preload
Slide 135
Slide 135 text
18% improvement
Slide 136
Slide 136 text
36% improvement
Slide 137
Slide 137 text
Render
Slide 138
Slide 138 text
HTML Streaming
reduced TTFB by 30%
(200ms), increasing time
user’s spent in the app.
Nicolas Gallagher, Technical lead for Twitter Lite
Slide 139
Slide 139 text
No content
Slide 140
Slide 140 text
4x improvement to
render perf by using
requestIdleCallback() to
defer JS loading of
images.
Nicolas Gallagher, Technical lead for Twitter Lite
Slide 141
Slide 141 text
Heavy image decode
Lower image decode
Slide 142
Slide 142 text
No content
Slide 143
Slide 143 text
Adapt intelligently
H
E
I
G
H
T
Size appropriately
WIDTH
IMAGE DECODE
Compress carefully Take care with tools
Prioritize critical images
HIGH
LOW
Lazy-load the rest
Choose the right format
Image
Optimisation
Slide 144
Slide 144 text
images.guide
Slide 145
Slide 145 text
Data Saver Mode introduced up to 70% savings for Twitter Lite
Do this with the browser using the Save-Data client hint
Slide 146
Slide 146 text
Precache
Slide 147
Slide 147 text
This is a headline
Followed by a subhead
This is body copy and it goes a little like this and Lorem ipsum
dolor sit amet, consectetur adipiscing elit. This is body copy and
it goes a little like this and Lorem ipsum dolor sit amet,
consectetur adipiscing elit.
Application Shell
A skeleton representing the
user interface that can be
offline cached & instantly
rendered on repeat visits.
Slide 148
Slide 148 text
Before Service Worker
After Service Worker
Slide 149
Slide 149 text
Lazy-load
Slide 150
Slide 150 text
No content
Slide 151
Slide 151 text
Before code-splitting
Slide 152
Slide 152 text
webpack-web.config.js
const plugins = [
// extract vendor and webpack's module manifest
new webpack.optimize.CommonsChunkPlugin({
names: [ 'vendor', 'manifest' ],
minChunks: Infinity
}),
// extract common modules from all the chunks (requires no
'name' property)
new webpack.optimize.CommonsChunkPlugin({
async: true,
children: true,
minChunks: 4
})
];
Slide 153
Slide 153 text
After code-splitting
bit.ly/twitterlite-perf
bit.ly/twitter-casestudy
Slide 154
Slide 154 text
No content
Slide 155
Slide 155 text
No content
Slide 156
Slide 156 text
https://meowni.ca/font-style-matcher/
Slide 157
Slide 157 text
https://www.zachleat.com/web/comprehensive-webfonts/
“Comprehensive
Web Fonts”
Slide 158
Slide 158 text
No content
Slide 159
Slide 159 text
No content
Slide 160
Slide 160 text
Link: ; rel=preload; as=font;
type='font/woff'
Slide 161
Slide 161 text
Heaviest use of rel=preload is for Web Fonts
HTTPArchive
Slide 162
Slide 162 text
Preloading Web Fonts = 50% (1.2s)
improvement in time-to-text-paint
Slide 163
Slide 163 text
Control font performance
with font-display
auto: uses whatever font display strategy the user-agent uses
block: draws "invisible" text at first if the font is not loaded, but swaps
the font face in as soon as it loads
swap: draws text immediately with a fallback if the font face isn’t
loaded, but swaps the font face in as soon as it loads
fallback: font face is rendered with a fallback at first if it’s not loaded,
but the font is swapped as soon as it loads
optional: if the font face can’t be loaded quickly, just use the fallback
Chrome 60
Slide 164
Slide 164 text
No content
Slide 165
Slide 165 text
No content
Slide 166
Slide 166 text
bit.ly/font-subsetting
Slide 167
Slide 167 text
https://fonts.googleapis.com/css?family=Inconsolata
https://fonts.googleapis.com/css?family=Inconsolata&text=Hello
Web Font Subsetting
~3KB
~880 bytes
Supported by Google Fonts
Slide 168
Slide 168 text
/* Small subset, normal weight */
@font-face {
font-family: whatever;
src: url('reg-subset.woff')
format('woff');
unicode-range: U+0-A0;
font-weight: normal;
}
The browser can also handle subsetting!
https://jakearchibald.com/2014/minimising-font-downloads/
/* Large subset, normal weight */
@font-face {
font-family: whatever;
src: url('reg-extended.woff')
format('woff');
unicode-range: U+A0-FFFF;
font-weight: normal;
}
Chrome 36
Firefox 44
Slide 169
Slide 169 text
CSS Font Loading API
https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/webfont-optimization
const font = new FontFace("Awesome Font", "url(/fonts/awesome.woff2)", {
style: 'normal', unicodeRange: 'U+000-5FF', weight: '400'
});
// don't wait for the render tree, initiate an immediate fetch!
font.load().then(function() {
// apply the font (which may re-render text and cause a page reflow)
// after the font has finished downloading
document.fonts.add(font);
document.body.style.fontFamily = "Awesome Font, serif";
// OR... apply your own render strategy here...
});
Chrome 35
Firefox 41
Slide 170
Slide 170 text
Use System Fonts when you can
The fastest font is one that doesn’t need to load.
Try font-display: optional;
If a Web Font can’t load fast, load a fallback instead. If the Web Font is
cached, it’ll get used the next time the user loads the page.
Try to request Web Fonts with a higher priority
If Web Fonts are a critical to your UX, preload them to minimize FOIT.
Try subsetting to limit the range of Web Font characters needed
Subsetting removes characters & Open-Type features from fonts, reducing
file size. Google Fonts, TypeKit & Font Squirrel support it. Be careful with use.
Try the CSS Font Loading API if you need more control
Track font download progress & apply once fetched, manipulate font faces
and override default lazy load behavior.
S
Have a Web Font Loading Strategy
@addyosmani
Slide 171
Slide 171 text
No content
Slide 172
Slide 172 text
Streams API
bit.ly/streams-ftw
Progressive Loading: HTML
Slide 173
Slide 173 text
in body
bit.ly/progressive-css
Progressive Loading: CSS
Slide 174
Slide 174 text
in body
bit.ly/progressive-css
Progressive Loading: CSS
…
…
…
…
Slide 175
Slide 175 text
medium.com/reloading
Slide 176
Slide 176 text
No content
Slide 177
Slide 177 text
No content
Slide 178
Slide 178 text
No content
Slide 179
Slide 179 text
No content
Slide 180
Slide 180 text
No content
Slide 181
Slide 181 text
No content
Slide 182
Slide 182 text
No content
Slide 183
Slide 183 text
No content
Slide 184
Slide 184 text
No content
Slide 185
Slide 185 text
No content
Slide 186
Slide 186 text
No content
Slide 187
Slide 187 text
No content
Slide 188
Slide 188 text
No content
Slide 189
Slide 189 text
No content
Slide 190
Slide 190 text
No content
Slide 191
Slide 191 text
No content
Slide 192
Slide 192 text
No content
Slide 193
Slide 193 text
No content
Slide 194
Slide 194 text
No content
Slide 195
Slide 195 text
No content
Slide 196
Slide 196 text
https://medium.com/dev-channel/treebo-a-react-and-preact-progressive-web-app-
performance-case-study-5e4f450d5299
next do webpack bundle analyzer
Slide 197
Slide 197 text
No content
Slide 198
Slide 198 text
No content