WordPress Tutorials December 31, 2019

WordPress Caching – How It Works and Why You Should Use It!

Alexander Newnham

7 min read
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If you have hosted any WordPress websites then you almost certainly have heard of ‘caching’. Many dedicated WordPress hosts will offer caching of some type or form and you’re also spoilt for choice when it comes to caching plugins. So, what exactly is caching and how does it help your website?

What is Caching?

WordPress is a dynamic system that generates viewable web pages for your end-users. The process it runs through to do this is pretty complex and involves pulling information from your website database. Queries go back and forth and the information pulled from the database is rendered as the final web page that everyone sees. Each time a web page is generated, your hosting has to call on a number of server resources to carry out this process. Server resources are limited and if you have a large amount of traffic this can cause problems. This is because the server won’t be able to keep up with all the demands being made on it to run the processes required by WordPress to render a web page.

To get around the issue of WordPress continually making calls to the database, and in doing so placing a burden on the server, caching is used. Caching is the term used for creating static copies of your page or post which are then served up to the end-user. In effect, WordPress runs the processes required once to generate the page the first time someone visits it. This page is then cached for future visitors who get served the static page.

The Benefits of Caching

There are two key benefits of caching your WordPress website:

  • Speed: Because the server only has to provide a static copy of a web page, the number of processes it has to run are far fewer. This results in much faster load times for websites that are cached. Speed is critical for a website… not only will your website users abandon your site if it takes too long to load but Google will also penalize you resulting in lower rankings.
  • Server Load Reduction: Because the server only has to render a web page once before it is cached, each subsequent request for that page only requires a static copy to be served. This means the load on the server is significantly lower which is especially helpful during traffic spikes when, if the server was forced to render each page request, it would likely crash.

The Problems with Caching

Caching is a great option for almost all WordPress websites and the performance gains can be significant. This isn’t to say however it doesn’t come with problems, with the primary issue being that updates made to the site are not reflected in the live version that is being shown to your website visitors.

As discussed, a caching system saves a static copy of your website page or post. Because WordPress is dynamic this content may change for a number of reasons. The first is a user update whilst the second may be an update pushed out by some dynamic code (such as the date changing in the footer of your website). In either situation, you are going to want this fresh content to be reflected on the live version of your website.

Caching can sometimes mean this doesn’t always happen as the caching engine may fail to see the changes made to the page and as a result continues to serve the ‘old’ static copy of your website.

This is often a problem for developers who are making changes to the theme code of their live site. The caching plugin won’t spot these updates meaning that one thing ends up showing on the developer’s screen but another on the end-user screen.

How well your caching works and whether or not it does a good job of spotting these updates depends on the caching solution you chose to deploy. In all cases though, this problem can be easily fixed by ‘flushing’ the cache. This means telling your cache to clear itself. It will then rebuild and moving forward serve up the correct up-to-date static version of your website.

Note: Whilst flushing the cache is an easy win solution for ensuring the correct version of your website is displayed, it does come with the downside that the entire cache has to be rebuilt. This can place a significant strain on your server, especially if you have a large website. As such, it’s sometimes preferable to clear the cache of just a single page or, better still, to move to a more sophisticated caching solution that does a better job of updating itself.

Caching Options

You have two main choices when it comes to caching for your WordPress website… to use a caching plugin (we’ve suggested some below) or to choose a managed WordPress host that offers caching as part of their platform.

Plugins offer a quick, easy and often free way to add caching to your WordPress site. As with most plugins, they vary in quality however and can require some expertise to setup and manage. Performance will likely vary significantly from plugin to plugin and you’ll need to carefully test to ensure you’re getting the results you expect from the plugin in combination with your hosting.

Caching offered by a managed WordPress host (like Pressidium) can often be more reliable as it’s been carefully developed and tuned to work with their hosting setup. As it will also likely operate at the server level it will almost certainly be faster. It should also require zero setup on your part and work ‘right out of the box’.

If using a managed host like Pressidium isn’t for you and you want to go it alone on the caching front then try out one of these caching plugins.

W3 Total Cache

With 1+ million active installations, W3 Total Cache is certainly a popular choice. Boating of at least 10 x improvement in overall site performance when fully configured, it is a great way to boost your page load speeds whilst reducing server load. Extensively tested, it should also work with most web hosts. Just be prepared to spend some time setting it up as it can be a little complex to get started with.

WP Super Cache

With an impressive 2+ million active installations, WP Super Cache is a leader in the caching plugin market. Developed by Automattic, the team behind WordPress itself, you can be confident it should deliver an excellent caching solution for your WordPress site. It’s very simple to setup with a limited range of customizations available making it the ideal choice for those of you who just want to load it up and get going asap. It’s also under regular development giving you the comfort that it should stay up-to-date and secure.

Whatever option you choose, WordPress caching is an absolute must for almost all WordPress websites. If you’ve yet to add caching to your site, then it’s one of the easiest wins for performance improvements you can do and well worth the time needed to get it setup.

Enjoy hassle free website caching with Pressidium!

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