Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
FSTO: Re-evaluating Front-end Peformance Best P...
Search
benvinegar
November 15, 2015
Programming
9
1k
FSTO: Re-evaluating Front-end Peformance Best Practices
Full Stack Toronto 2015
benvinegar
November 15, 2015
Tweet
Share
More Decks by benvinegar
See All by benvinegar
Getting the most out of JavaScript errors
benvinegar
1
340
JavaScript Error Reporting (and Why We Can't Have Nice Things)
benvinegar
0
230
Re-evaluating Front-end Performance Best Practices
benvinegar
15
1.6k
Other Decks in Programming
See All in Programming
AI時代のUIはどこへ行く?
yusukebe
18
9k
パッケージ設計の黒魔術/Kyoto.go#63
lufia
3
440
「手軽で便利」に潜む罠。 Popover API を WCAG 2.2の視点で安全に使うには
taitotnk
0
870
時間軸から考えるTerraformを使う理由と留意点
fufuhu
16
4.8k
「待たせ上手」なスケルトンスクリーン、 そのUXの裏側
teamlab
PRO
0
560
🔨 小さなビルドシステムを作る
momeemt
4
690
ユーザーも開発者も悩ませない TV アプリ開発 ~Compose の内部実装から学ぶフォーカス制御~
taked137
0
190
機能追加とリーダー業務の類似性
rinchoku
2
1.3k
Android 16 × Jetpack Composeで縦書きテキストエディタを作ろう / Vertical Text Editor with Compose on Android 16
cc4966
2
260
意外と簡単!?フロントエンドでパスキー認証を実現する WebAuthn
teamlab
PRO
2
770
Putting The Genie in the Bottle - A Crash Course on running LLMs on Android
iurysza
0
140
Testing Trophyは叫ばない
toms74209200
0
890
Featured
See All Featured
How to Ace a Technical Interview
jacobian
279
23k
Performance Is Good for Brains [We Love Speed 2024]
tammyeverts
12
1.1k
How to Create Impact in a Changing Tech Landscape [PerfNow 2023]
tammyeverts
53
2.9k
The Cult of Friendly URLs
andyhume
79
6.6k
We Have a Design System, Now What?
morganepeng
53
7.8k
Building a Scalable Design System with Sketch
lauravandoore
462
33k
Building Adaptive Systems
keathley
43
2.7k
Reflections from 52 weeks, 52 projects
jeffersonlam
352
21k
A better future with KSS
kneath
239
17k
Unsuck your backbone
ammeep
671
58k
Site-Speed That Sticks
csswizardry
10
820
Helping Users Find Their Own Way: Creating Modern Search Experiences
danielanewman
29
2.9k
Transcript
re-evaluating front-end performance best practices
@bentlegen
None
http://getsentry.com
car·go cult
ccccccejlfevnigejevgjkglrc hibhjrtcjlngnfblfb cargo cult science
cargo cult web performance
how did we get here?
deprecated books 2007 2009 2010
stackoverflow answers
analysis tools
analysis tools 2014 2013
practices on live websites
conference talks
today’s agenda • hostname sharding • for-loop array length caching
• dynamic script insertion
hostname sharding
in the beginning (HTTP 1.0)
with more connections 2 4 8 www www www
with hostname sharding 2 2 2 www www1, www2 www1
www2 www3 www4
still common Website # Static Hosts plus.google.com 4 tumblr.com 4
alibaba.com 4 theverge.com 4 ebay.com 6 businessinsider.com 6 netflix.com 11!
None
not a big deal anymore
browser connections/origin Browser # HTTP / origin Chrome 42 6
Firefox 37 8 Safari 7 6 IE 8, 9 6 IE 10 8 IE 11 13 bit.ly/rprf-bscope
chrome caps parallel image requests at 10 anyways bit.ly/rprf-bscope
rise of https stalled/ proxy negotiation dns lookup connection +
tls/ssl time-to- first-byte download tls/ssl handshake
and http/2 will make all this irrelevant anyways
“2 domains for non- [HTTP2] modern browsers” – Souders in
2013 bit.ly/rprf-2domains
etsy case study • 4 image domains → 2 •
50-80 ms faster for image heavy pages • 30-50 ms faster overall • up to 500ms faster on mobile bit.ly/rprf-etsy
the web’s moving on Website # Static Hosts netflix.com* 1
nytimes.com 1 youtube.com 2 twitter.com 2 facebook.com 2 pinterest.com 2 bbc.co.uk 2 etsy.com 3
looping
specifically array length caching in for loops
for (var i = 0, len = arr.length; i <
len; i++) { // do stuff } for (var i = 0; i < arr.length; i++) { // do stuff } vs
None
None
None
does it still hold?
cache vs no cache Chrome 42 Firefox 37 Safari 7
IE9+ IE8 ops/second (normalized), bigger is better cache no cache 78%
V8 (and other browsers) recognize this pattern bit.ly/rprf-v8opt
None
uncached version
cached version
“we should start assuming that our code is optimized” -
Vyacheslav Egorov, V8 bit.ly/rprf-v8opt
if you can trivially optimize it, the browser (probably) can
too
mobile disagrees, a little Chrome 41 (Android 5.1) Firefox 34
(Android 5.1) Safari (iOS 8) ops / second (normalized), bigger is better cache no cache 95%
new in es6 for (x of arr) { … }
dynamic script insertion
blocking scripts (2009) <script src=“/vendor.js”></script> <script src=“/app.js"></script> <img src=“/logo.gif”/> <link
rel=“stylesheet” type=“text/css” href=“/app.css”/> <iframe src=“/widget.html”/> vendor.js finishes app.js starts img, css, iframe
dynamic script insertion <script> var script = document.createElement('script'); script.src =
'/app.js'; document.getElementsByTagName('head')[0] .appendChild(script); </script> all load in parallel
None
None
you’ve used this • analytics: GA, Mixpanel, Chartbeat, Wordpress •
widgets: Disqus, Facebook Comments • JS module loaders: RequireJS, LabJS • script managers: Google Tag Manager, Segment
small problem: CSS Object Model
CSS Object Model (CCSOM) <link rel="stylesheet" type="text/css" href="/ main.css"/> <script>
window.getComputedStyle(document.body).margin; </script> can’t execute until CSS ready
CSSOM + dynamic script insertion <link rel="stylesheet" type="text/css" href="/ main.css"/>
<script> var script = document.createElement('script'); script.src = '/app.js'; document.getElementsByTagName('head')[0] .appendChild(script); </script> can’t execute until CSS ready
dynamic script insertion scripts execute inline scripts can’t execute until
CSSOM ready; downloading is delayed
blocking 2nd script downloads after 1st executes 1st script preloaded
1st script executes
blocking with Chrome 1st and 2nd script preloaded 1st and
2nd script execute (blocked for CSSOM)
2014
3rd option: async attribute <script async src="/app.js"></script>
ideal: async attribute scripts execute before CSS finished all 3
resources download in parallel
we should probably start using async
new: GA + async attr
closing thoughts
don’t always believe what you read on the internet
benchmark your own stuff
benchmark your own stuff every few years
always bet on browsers (and JS engines)
thanks
acknowledgements • performance research: Steve Souders, Ilya Grigorik, Guy Podjarny,
Vyacheslav Egorov, Jonathan Klein, Paul Irish, Nicholas Zakas • photos: Christian Junker, André Hofmeister, “My aim is true” • me: Ben Vinegar (@bentlegen) • Sentry plug: http://getsentry.com