Front-End Performance Optimization in WordPress
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Data from major Internet providers like Google, Amazon and Akamai has shown that how fast a website loads significantly affects user behavior. And because users don’t like slow sites, Google uses load time as a factor in computing PageRank results. In short: It pays to be fast. There are a lot of factors that can affect your site’s performance. While some are dependent on your hosting environment, there are plenty of factors beyond server/internet speed (and the obvious sheer number of bits to be loaded) that affect your page load time, such as HTTP connections, DNS lookups, and asset load sequencing. If you’re a front-end developer and you’re serious about building websites that load as fast as possible, come learn about techniques (such as non-blocking Javascript) you can use in your markup and themes — whether on WordPress or some other system — to help things load as quickly as possible. We’ll also review tools you can use to assess whether your site is doing all it can to load quickly.
Transcript of Front-End Performance Optimization in WordPress
SPEED MATTERSSEO - UX - Sales - Mobile
OUR ENEMIES
Payload size Bloated DOM & CSS HTTP connections JavaScript blocking
DNS lookups
NOT COVERED
Apache/mySQL config !
Using a CDN !
Choosing a good host
REDUCE PAYLOADa.k.a. front-end performance 101
REDUCE ASSET SIZES
Minify your JS and CSS (and HTML)
Load properly-sized images
Use right image filetypes (gif/jpg/png/svg)
DEFER ASSET LOADING
“lazy load” images when they appear in browser window
Use async/defer <script> attributes
!
Also, load pre-cached stuff!
<script defer async src="script.js"></script>
TRICKING WP_ENQUEUE_SCRIPTfunction add_async( $url ) { if (strpos($url, '#async')===false) return $url; else if (is_admin()) return str_replace('#async', '', $url); else return str_replace('#async', '', $url)."' async"; } add_filter('clean_url', 'add_async', 11, 1);
wp_enqueue_script('demo', '/js/myscript.js#async' );
USING GOOGLE’S JQUERY
wp_deregister_script('jquery'); wp_register_script( 'jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js', array(), '1.11.0' );
BLOATED DOM & CSSmake it clean before you make it mini
MORE ELEMENTS = SLOWER<body class="page"> <div id="wrapper"> <div id="page"> <div id="main"> <div class="main-side"> <aside id="sidebar"> ... </aside> </div> </div> </div> </div></body>
You can do a count with: !$(‘*’).length; !or !document. getElementsByTagName(‘*”). length
SIMPLE SELECTORS
html body div#main article#post-22 p a.inline { property: value; }
.inline { property: value; }
VS.
ul li {} is slower than ul > li {} which is slower than .ul-li {}
HTTP CONNECTIONSyour biggest obstacles to fast loads
HTTP CONNECTIONS
Each asset (script, image, css file, font, etc) is retrieved via an HTTP
connection.
Each connection takes a moment to start due to overhead.
HTTP HEADERS
REDUCING CONNECTIONS
Combine CSS Files
Combine JS Files
Use CSS Sprites
Avoid images in favor of CSS
Don’t load stuff you don’t need*
COMBINING CSS FILES
Use a tool like SASS that combines them for you
Only write a single style.css
Use a plugin (e.g. W3 Total Cache) to combine (& compress!) them for you.
COMBINING JS FILES
Use a plugin (e.g. W3 Total Cache) to combine+compress
them for you.
Manually put all your jQuery plugins into a single file.
COMBINING JS FILES
WordPress is especially prone to loading lots of JS files
It’s worth the effort to mitigate against this. Seriously.
CSS SPRITES
Put all your images into a single file, and use CSS to position the
background properly.
CSS SPRITE EXAMPLE
.sprite-ben { height: 117px; width: 91px; background-image: url('img/sprite.png'); background-position: 0 -525px; background-repeat: no-repeat; }
overall sprite.png file measures 304 x 910
but my headshot is a small part
DON’T USE IMAGES
CSS3 provides alternatives:
Gradients
Rounded Corners
Text and box shadows
Rotation
JAVASCRIPT BLOCKINGAnd sequential loading general
SEQUENTIAL VS. PARALLEL
Browsers can load some assets in parallel, such as CSS files, images, and fonts. This is good.
But some assets —JS files — are loaded in sequence and block others.
CSS AND SCRIPTS
JS should be at bottom of page.
CSS should go at the top of your page and be loaded via
<link> not @import
IN WORDPRESS
wp_enqueue_script( $handle, $src, $deps, $ver, $in_footer );
Set to TRUE
DNS LOOKUPShidden time thieves
DNS LOOKUPS
Every domain mentioned on your page needs to be
resolved to an IP (20-120 ms) !
But too few domains is bad too.
TOOLS
FOR MORE
Google “Steve Souder”
https://developers.google.com/speed/docs/best-practices/rules_intro
!http://developer.yahoo.com/yslow/
!https://developers.google.com/speed/
pagespeed/
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