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367 • Combine CSS and JavaScript - There are many great resources available on the Web for consolidating, combining, and compressing your CSS and JavaScript files. WordPress users should check out WP Minify http://digwp.com/u/344, which uses the Minify PHP-5 application http://digwp.com/u/356 used to combine multiple CSS and JavaScript files, compress their contents, and serve the results with HTTP encoding (gzip or deflate) and headers that allow optimal client-side caching. • Progressive image-loading - Instead of loading all of your images at once, delay loading of images in long web pages until the user scrolls down to the next section of the web page. This is opposite of preloading all of your images at once. With progressive image-loading, users will experience a slight delay in the loading of images as they scroll down the page, but for pages with lots of images, progressive loading can reduce the number of simultaneous HTTP requests and greatly improve performance for the initial page load. Check out the jQuery plugin, Lazy Load http://digwp.com/u/493, to easily implement progressive image loading on your site. • Use a content-distribution network - A Content Delivery Network (CDN) is a network of computers cooperating to deliver content for web sites. Using additional servers to deliver images, downloadables, and other static files reduces the load of your primary server while improving the performance and scalability of the overall website. Some commercially available CDNs include: • Akamai Technologies - http://digwp.com/u/364 • Amazon CloudFront - http://digwp.com/u/358 • BitGravity - http://digwp.com/u/359 • CacheFly - http://digwp.com/u/360 • Internap - http://digwp.com/u/361 • Limelight Networks - http://digwp.com/u/363 • Mirror Image Internet - http://digwp.com/u/365 • SteadyOfoad - http://digwp.com/u/362 368 While working to reduce the overall number of HTTP requests for your site, there are several ways to check how many requests are being made from your pages. By simply opening a text editor and scanning your CSS file for all instances of the “url()” value, you can determine how many images are being called just for your design. In your browser, you can also check the source code of your pages and examine the number of files linked to in the <head> area. By searching your source code for all instances of “<img”, you can see how many regular images are being called. If you are using Firefox, the awesome and absolutely essential Firebug extension http://digwp.com/u/366 can be used with Yahoo’s helpful YSlow add-on http://digwp.com/u/379 to analyze your site’s performance in real time, with nice graphical representations showing many different aspects of your site, including the overall number and duration of HTTP requests. Here is a screenshot showing how Firebug together with YSlow can help you analyze the number of HTTP requests made by any page: 369 9.5.6 Plugin Maintenance Many articles on the Web will advise you to disable unused plugins as a way of optimizing your site. While this is partially true, there is much more to the story. It all begins when deciding which plugins to install. Do some research and make an informed decision before implementing each of your plugins. Every plugin that you install requires resources and may decrease performance. Plugins also affect performance in a cumulative fashion. Even so, I have seen sites running 50 or more plugins that load very quickly. Just keep in mind that, unless you know what you are doing, loading up on unnecessary plugins can really slow things down. Next, once you begin installing plugins, remember to test as each one is installed. Don’t just slap it in there and walk away – take the time to surf your site and examine its performance with the newly installed plugin(s) installed. If you find that they are slowing things down, reconsider your choice and search for better options. Otherwise, do what you can to offset the reduced performance, perhaps by caching (see Section 9.5.2 in this chapter). Optimizing your database is a great way to improve site performance. There are numerous ways to do so, including the following: • Manual SQL query - using the “OPTIMIZE TABLE” command, it is possible to optimize any specific table or group of tables. Use this format, replacing the example terms with your table names: OPTIMIZE TABLE `feeds`, `items`, `options`, `tags` • Using phpMyAdmin - check all tables in your database and select “Optimize” from the dropdown menu. • Use a plugin - Joost De Valk’s Optimize DB plugin makes it easy to optimize your database: http://digwp.com/u/369 Optimize Your WordPress Database • Use a different plugin - Another good plugin for optimizing and cleaning up your database is WP-Optimize http://digwp.com/u/370. Also check out WordPress Database Table Optimizer http://digwp.com/u/371 to automate the optimization process. • Use a completely different plugin - The WP DBManager plugin http://digwp.com/u/334 also makes it easy to optimize your database, along with a whole bunch of other great database-management features including automatic database backup and more. Regardless of your method of choice, it is good practice to optimize your database on a periodic basis to help ensure optimal site performance. 370 Then, as you continue to take control of your plugin arsenal, keep an eye on any that may have been useful at one time but now are useless. Uninstall any obsolete and unused plugins immediately. Every time you load a page on your site, all of your plugins are loaded in the background. Thus, any plugins that you can remove from this equation will provide an immediate performance boost. Also, as mentioned above, keep your plugins updated. Whenever you see that a new version of the plugin is available, take the time to check it out and then upgrade as soon as possible. Staying current with plugins is a good idea because they usually feature improved code, tighter security, and better features. Finally, once you decide to disable a plugin, remove it completely. Don’t leave it sitting there in a disabled state in your Admin area. Uninstall it, and make sure that any peripheral files that may have been related to the plugin are also removed. Hopefully, any plugin that you decide to install will provide a complete “Uninstall” option that cleans up after itself in the WordPress database, but if not, you may want to go in and manually remove all traces of it. 9.5.7 Database Maintenance If your theme is the heart of WordPress, then your database is its brain. The database contains all of the settings, comments, posts, plugin options, and administrative data required for your site to function properly. When this data becomes corrupted or is poorly optimized, performance may suffer. A good practice to get into involves optimizing and backing up your database at regular intervals, depending on the use and scope of your site. Highly active sites should optimize their database every day, while less-active sites may be fine optimizing once a week or less. You should also take every opportunity to clean up your database of unnecessary data. For example, after installing, testing, configuring, and uninstalling plugins, you should examine your database for any tables or options that may no longer be necessary. If the plugin developer did their job, their plugin will include a complete uninstall option that cleans up the database for you. Unfortunately, this is not always the case. Too Many Plugins? As this book goes to press, we are currently running a poll at the Digging into WordPress companion site that asks, “How Many Plugins do You Use?” Drop by and vote if the poll is still open when you read this, otherwise check in to see the results: http://digwp.com/u/367 371 9.5.8 Other Optimization Techniques There are many ways to optimize your site and improve performance for your visitors. Here are a few more ideas that are well-worth the effort. Split long posts into multiple pages WordPress enables you to split up long posts into individual pages using the <! nextpage > tag in your posts. This trick is not for all posts, but for those super- long articles with lots of images and stuff, it may really help to speed things up. Limit the number of posts on archive and index pages The idea here is to reduce the overall size of your web pages by displaying fewer posts. Instead of, say, 20 posts on your homepage, you can use a plugin such as Custom Query String Reloaded http://digwp.com/u/373 to limit the number of posts that are displayed. By doing similar for other types of page views, you can customize page size in granular fashion. Specify far-future expires or cache-control headers For static resources such as images, CSS and JavaScript files, a great way to decrease load time for your regular visitors is to specify far-future “Expire Headers.” By setting an expiration date of, say, a month for your image files, visitors’ browsers will know not to re-fetch them, thereby reducing their load-time significantly. Here is an example showing an HTAccess technique used for three common types of images: # EXPIRATION HEADERS FOR IMAGES # note: 2592000 seconds = 1 month ExpiresActive On Cache Your Database Improve database performance by caching your database queries. Check out the DB Cache plugin to cache your queries and speed up the loading of your site. http://digwp.com/u/368 372 ExpiresByType image/gif A2592000 ExpiresByType image/png A2592000 ExpiresByType image/jpg A2592000 ExpiresByType image/tif A2592000 ExpiresByType image/ico A2592000 Just keep in mind that with cache-control headers in place, you will need to change the file name of any files that are being cached in order for them to be refreshed in the user’s browser. Reduce image sizes Obviously, large images require more time to load than smaller ones. There are millions of articles out there explaining how to optimize your images, so we won’t reinvent the wheel here. Instead, let us point out several avenues of image optimization that will help you determine the best approach: • Online image optimization tools - There are many great online services such as Smush.it http://digwp.com/u/374 or punypng http://digwp.com/u/375 that make it easy to upload and optimize your image sizes. Best of all, these free online services work on JPEG, GIF, and PNG images. Both services use “lossless” compression techniques to ensure that your images do not lose any of their original visual quality. • Ofine optimization programs - For more control over the details of your image optimization, check out OptiPNG http://digwp.com/u/376 or PNGcrush http://digwp.com/u/377. Either of these powerful command-line programs will remove unnecessary data from your PNG images without reducing image quality. Both are excellent programs that work beautifully. • Optimization during image creation - Arguably the best way to optimize your images is to create them optimally to begin with. There are many ways to do this, and there are plenty of excellent articles that will help you use programs such as Photoshop to take advantage of its image-optimization tools. 373 Hardcode database calls to improve performance Speed things up by eliminating unnecessary calls to the database. A classic example of this is seen in the header.php file of most WordPress themes. Here is a typical example: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" <?php language_attributes(); ?>> <head prole="http://gmpg.org/xfn/11"> <meta http-equiv="Content-Type" content="<?php bloginfo('html_type'); ?>; charset=<?php bloginfo('charset'); ?>" /> <title><?php wp_title('«', true, 'right'); ?><?php bloginfo('name'); ?></title> <link rel="stylesheet" href="<?php bloginfo('stylesheet_url'); ?>" type="text/css" /> <link rel="pingback" href="<?php bloginfo('pingback_url'); ?>" /> If you are releasing your theme for public consumption, the database calls made by these template tags make it easy to display the correct information on any WordPress-powered site. For themes that do not require the convenience that these template tags provide, however, it is possible to reduce the number of calls made by replacing the tags with their plain-text values. If you go through your theme files, you will see there are many of these dynamic calls that may be replaced with static values. To help illustrate, here’s what the previous code would look like after replacing the dynamic tags with their corresponding, site-specific, plain-text values: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en-US"> <head prole="http://gmpg.org/xfn/11"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Digging into WordPress</title> 374 <link href="http://digwp.com/wp-content/themes/DiggingIntoWordpress-1/style.css" rel="stylesheet" type="text/css" media="screen" /> <link rel="pingback" href="http://digwp.com/xmlrpc.php" /> Disable unused/unnecessary plugins Plugins consume resources. Running plugins you don’t need is stupid. Go through your list and uninstall/delete any that you no longer need. Trust us, you’ll be glad you did. To Infinity, and Beyond As we have seen in this chapter, there will always be a way to improve the performance of your WordPress-powered website. Out-of-the-box, it’s going to work just fine for just about anything, but that is no reason to get complacent. Even with the smallest amount of effort, it is possible to improve your existing functionality and further optimize your current setup. From simply installing a few caching plugins to manually implementing custom functions, your site’s maintainability, security, and performance can be advanced as far as you are willing to go. 375 Screenshot of WordPress- founder Matt Mullenweg’s personal website. Thanks Matt. http://ma.tt 376 In the beginner‘s mind there are many possibilities, but in the expert‘s there are few. – SHUNRYU SUZUKI . Akamai Technologies - http://digwp.com/u/364 • Amazon CloudFront - http://digwp.com/u/358 • BitGravity - http://digwp.com/u/359 • CacheFly - http://digwp.com/u/360 • Internap - http://digwp.com/u/361 . this chapter, there will always be a way to improve the performance of your WordPress- powered website. Out-of-the-box, it’s going to work just fine for just about anything, but that is no reason. corresponding, site-specific, plain-text values: <!DOCTYPE html PUBLIC " ;-/ /W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html
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