WCEU: Seven Times Faster : A Study in frontend Optimization

Wed 29 Oct 1969 ~ ucla$ ░

Wed 29 Oct 1969 ~ ucla$ lo ░ gin

Wed 29 Oct 1969 ~ ucla$ lo ░ ░

Seven times faster:   a study in front-end optimisation Peter
Wilson • peterwilson.cc • @pwcc

WordPress is slow

Front-end code is slow

Bytes on the page

Total page size (MB) Nov 2011 - March 2016 0.5
1.0 1.5 2.0 2.5 1 Nov '11 15 May '12 1 Dec '12 15 Jun '13 1 Jan '14 15 Jul '14 1 Feb '15 15 Aug '15 1 Mar '16 httparchive.org/trends.php, March 2016

Assets per page Nov 2011 - March 2016 20 40
60 80 100 120 1 Nov '11 15 May '12 1 Dec '12 15 Jun '13 1 Jan '14 15 Jul '14 1 Feb '15 15 Aug '15 1 Mar '16 httparchive.org/trends.php, March 2016

Webfonts Multiple of Nov 2011 (bytes) 2 4 6 8
10 12 14 16 18 1 Nov '11 15 May '12 1 Dec '12 15 Jun '13 1 Jan '14 15 Jul '14 1 Feb '15 15 Aug '15 1 Mar '16 httparchive.org/trends.php, March 2016

Load time httparchive.org/trends.php, March 2016

Load time Start render: 4.2 seconds

Load time Visually complete: 12.7 seconds

Load time Document complete: 15.23 sec

Two seconds

Walmart conversion rate slideshare.net/devonauerswald/walmart-pagespeedslide 0 - 1 1 - 2
2 - 3 3 - 4 4 - 5 5 - 6 6 - 7 7 - 8 8 - 9 9 - 10 10 - 11 11 - 12 12 - 13 13 - 14 14 - 15 15+

The average site kills conversions.

Measure a starting point

WebPageTest - webpagetest.org

Key metrics Document Complete Fully Loaded Load Time First Byte
Start Render Speed Index DOM Elements Time Requests Bytes In Time Requests Bytes In 3.770s 0.771s 1.789s 1834 397 3.770s 27 635 KB 4.072s 33 661 KB WebPageTest - webpagetest.org

Timeline view

Comparison timelines Additional blocking request in HTML Header Timed using
WebPageTest - pwcc.cc/wceu/blocking 0.5s 1.0s 1.5s 2.0s 0% 0% 0% 100% 0% 86% 100% Blocked Unblocked

53 / 100 Our PageSpeed score is you won’t believe
how  much it’s costing

What will get my visitors reading quickest? “ ”

Doing it wrong

JavaScript in the footer

All visitors have JavaScript disabled while it downloads. – Every
progressive enhancement advocate ever “ ”

wp_enqueue_script( 'pwcc-scripts', // handle '/functions.js', // source null, // no
dependancies '20160624-26', // version true // load in footer ); JavaScript, the WordPress way

wp_enqueue_script( 'pwcc-scripts', // handle '/functions.js', // source null, // no
dependancies '20160624-26', // version true // load in footer ); true // load in footer JavaScript, the WordPress way

wp_enqueue_script( 'pwcc-scripts', // handle '/functions.js', // source array( 'jquery' ),
// jQuery loads automatically '20160624-26', // version true // load in footer ); jQuery, the WordPress way

wp_enqueue_script( 'pwcc-scripts', // handle '/functions.js', // source array( 'jquery' ),
// jQuery loads automatically '20160624-26', // version true // load in footer ); array( 'jquery' ), // jQuery loads automatically jQuery, the WordPress way

<html> <head> <script src='jquery.js'></script> <script src='jquery-migrate.js'></script> </head> <body>  <script src='/functions.js'></script> jQuery, doing_it_wrong()

content. --> <script src='/functions.js'></script> </body> </html> jQuery, doing_it_wrong()

The WordPress way blocks rendering Daniel Zedda (CC) - ﬂic.kr/p/a6wwAh

function pwcc_jquery_to_footer() { if ( is_admin() ) return; wp_script_add_data( 'jquery',
'group', 1 ); wp_script_add_data( 'jquery-core', 'group', 1 ); wp_script_add_data( 'jquery-migrate', 'group', 1 ); } add_action( 'wp', 'pwcc_jquery_to_footer' ); jQuery, doing_it_wrong()

function pwcc_jquery_to_footer() { if ( is_admin() ) return; wp_script_add_data( 'jquery',
'group', 1 ); wp_script_add_data( 'jquery-core', 'group', 1 ); wp_script_add_data( 'jquery-migrate', 'group', 1 ); } add_action( 'wp', 'pwcc_jquery_to_footer' ); wp_script_add_data( 'jquery', 'group', 1 ); wp_script_add_data( 'jquery-core', 'group', 1 ); wp_script_add_data( 'jquery-migrate', 'group', 1 ); jQuery, doing_it_wrong()

content. --> <script src='/functions.js'></script> jQuery, the WordPress way

<html> <head>  </head> <body>  <script src='jquery.js'></script> <script src='jquery-migrate.js'></script> <script src='/functions.js'></script> </body> jQuery, doing_it_wrong()

<html> <head>  </head> <body>  <script src='jquery.js'></script> <script src='jquery-migrate.js'></script> <script src='/functions.js'></script> </body> </html> jQuery, doing_it_wrong() pwcc.cc/wceu/jqueryfooter

Asynchronous JavaScript

Asynchronous JavaScript <script type='text/javascript' src='/path/file.js' async></script>

Asynchronous JavaScript <script type='text/javascript' src='/path/file.js' async></script> async

function pwcc_async_js( $tag, $handle ) { switch ( $handle )
{ case 'pwcc-scripts' : $tag = str_replace( '></script', ' async></script', $tag ); } return $tag; } Asynchronous JavaScript

function pwcc_async_js( $tag, $handle ) { switch ( $handle )
{ case 'pwcc-scripts' : // Falls through case 'picturefill' : $tag = str_replace( '></script', ' async></script', $tag ); } return $tag; } Asynchronous JavaScript

switch ( $handle ) { case 'pwcc-scripts' : // Falls
through case 'picturefill' : $tag = str_replace( '></script', ' async></script', $tag ); } return $tag; } add_filter( 'script_loader_tag', 'pwcc_async_js', 10, 2 ); Asynchronous JavaScript

function pw_async_up() { wp_script_add_data( 'picturefill', 'group', 0 ); wp_script_add_data( 'pwcc-scripts',
'group', 0 ); } add_action( 'wp_enqueue_scripts', 'pw_async_up' , 99 ); Asynchronous JS in the header

function pw_async_up() { wp_script_add_data( 'picturefill', 'group', 0 ); wp_script_add_data( 'pwcc-scripts',
'group', 0 ); } add_action( 'wp_enqueue_scripts', 'pw_async_up' , 99 ); Asynchronous JS in the header pwcc.cc/wceu/asyncjs

Browsers initiate requests The blocking nature of HTTP 1

Blockers HTML

Blockers HTML CSS

Blockers HTML CSS IMG IMG IMG FONTS

Blockers HTML CSS IMG IMG IMG JS FONTS

Blockers HTML CSS IMG IMG IMG JS IFRAME FONTS

Waterfall WebPageTest - webpagetest.org

Waterfall HTML CSS IMG IMG IMG JS IFRAME FONTS

HTTP/2 An aside

Everything you know about performance is now wrong and former
best practices are now an anti-pattern and considered harmful.

These titles are considered harmful

Sites using HTTP/2 w3techs.com, March 2016

caniuse.com/http2, March 2016

Critical Path CSS

w3.org/TR/preload/

HTTP/2, without critical path CSS HTML CSS

HTTP/1, with critical path CSS HTML CSS

<html> <head> <style>html{font-family:sans-serif;-ms-text-size-adjust: 100%;-webkit-text-size-adjust:100%}body{margin:0}article, aside,details,figcaption,figure,footer,header,hgroup,main, nav,section,summary{display:block}audio,canvas,progress, video{display:inline-block;vertical-align:baseline} audio:not([controls]){display:none;height:0}[hidden], template{display:none}a{background:transparent}a:active, a:hover{outline:0}abbr[title]{border-bottom:1px
dotted} b,strong{font-weight:bold}dfn{font-style:italic}h1{font-

HTTP/1, with critical path CSS HTML CSS

HTTP/1, without critical path CSS HTML CSS

CSS, the WordPress way wp_enqueue_style( 'pwcc-style', // handle get_stylesheet_uri(), //
source array(), // no dependancies '20160624-26', // version 'all' // media );

Preloading CSS

Preloading CSS Link: </style.css>; rel=preload; as=style; nopush

Preloading CSS pwcc_preload_style( 'pwcc-style' ); // push pwcc_preload_style( 'pwcc-style', false
); // no push

Server push pwcc_preload_style( 'pwcc-style' );

Server push if ( is_cached( 'pwcc-style' ) ) { pwcc_preload_style(
'pwcc-style' ); } else /* file not cached */ { pwcc_preload_style( 'pwcc-style', false ); }

$version = '20160624-26'; setcookie( 'pwcc-style', $version, 0, '/' ); Server
push

is_cached() function is_cached( $handle, $version ) { if ( $version
=== $_COOKIE[ $handle ] ) { return true; } else { return false; } }

pwcc.cc/wceu/loadcss

Register loadCSS wp_register_script( 'pwcc-load-css', // handle '/loadcss.js', // file array(),
// dependencies "1.2.0", // version true // load in footer );

if ( ! is_cached( 'pwcc-style' ) && ! is_http2() )
{ print_style_inline( 'pwcc-style' ); wp_enqueue_script( 'pwcc-load-css' ); } Inline CSS

if ( ! is_cached( 'pwcc-style' ) && ! is_http2() )
{ print_style_inline( 'pwcc-style' ); wp_enqueue_script( 'pwcc-load-css' ); } Inline CSS pwcc.cc/wceu/rapidcss

Everything you know about performance is now wrong and former
best practices are now an anti-pattern and considered harmful.

Everything you know about performance is now twice as complicated.

Thank you Peter Wilson • peterwilson.cc • @pwcc

WCEU: Seven Times Faster : A Study in frontend ...

WCEU: Seven Times Faster : A Study in frontend Optimization

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