Speed: that's what your users want and require from your website or store. Especially on mobile devices where 53% of visits are abandoned if a mobile site takes longer than three seconds to load.

In a world where there's no room for slow pages, speed optimization is a key aspect of many online businesses that touches different areas of a website. And one of the most important steps in a speed and performance optimization process is setting up the right type of caching solution to gain even better performances.

Caching it's a technical matter just a little segment of WordPress users can take care of on their own, leaving room for a category of plugins that's always one of the most researched: caching plugins.

In fact, there are plenty of WordPress caching plugins you can find in the WordPress repository like W3 Total Cache, WP Super Cache, WP Fastest Cache, just to name a few of the most well-known. It's worth mentioning WP Rocket too, a premium plugin that in the last years has gained a lot of attention because of its good results.

So, how do these caching plugins work? What's the core problems they help you address? In this blog post, I'll share more insights on the nooks and crannies of what these caching plugins do and answer those questions you always wanted to ask a developer... but were afraid to ask!

Are you ready to get your answers? It's about time, let's dive in!

Question #1: What's caching in plain English?

It all starts with this question, which to a non-technical person or business owner might sound like impossible to understand and get an answer to. Have faith, dear friend!

Instead of trying to give you a short definition lacking technical (and scary) terms, there's nothing better than Peter Chester's example. Here it is:

What's caching?

During a WordPress talk, Peter asked the audience: 'What's 3,485,250 divided by 23,235?'
Everyone fell silent. Some people pulled out calculators to do the math, and finally, someone yelled out the answer after a few seconds.

Then the speaker asked the exact same question again. This time everyone was able to immediately call out the answer.

This is a great demo of the concept. The initial time-consuming process was done once, then after that, when the same question was asked, the answer was readily available, and delivered much faster.

The first visitor to a particular page on your site is 'asking the question' and your server provides the answer. The next time a visitor goes to the same page (or the first one comes back), and 'asks the same question', your server can provide the answer - the web page - much faster.

Roughly speaking, caching is similar to taking snapshots of a given page (or query) and storing them smartly so that, when requested again, your website doesn't have to do that exact process and can serve it faster. That "smart" storage can happen client-side, via your browser, and/or server-side, via your servers provided by your hosting providers.

Question #2: How do caching plugins work?

Caching plugins make a business owner's life easy by simplifying the entire caching process to an enormous extent. Given the complexity of it and the abundance of plugins for this purpose, we can summarize it by saying which aspects of a website could be interested by a caching plugin.

Here following you can find the top areas that are commonly touched by caching plugins:

  • HTML and CSS
  • Database
  • Images
  • Third-party scripts
  • Server-side elements

Pay attention here: a caching plugin won't cover all elements that a thorough WordPress optimization process will affect. WordPress developer and Codeable expert Josh Morley further elaborates:

If your hosting provider does not offer an inbuilt caching system, as many don’t, we would install a caching plugin like WP Rocket, which is my preferred plugin to use. But before we do anything, we'd take a backup of the site. After the caching plugin is installed, configured and tested, we would move on to other issues that slow down a site such as render blocking JS & CSS or the process of minification and concatenation.

Through a plugin, you'll never reach the same level of results a speed and performance specialist could guarantee as there are several technical advanced aspects involved in such projects. Yet, thanks to a properly configured plugin, you can improve your speed in a more convenient way, i.e. through the preferred plugin's settings.

Question #3: Do I need a plugin if my hosting provider has a caching service already?

Depending on which type of hosting your website is on, you could already have some sort of caching in place or the option to have it enabled by the service provider.

The one thing you should be aware of, though, is to stay away from piling a caching plugin onto a caching system your hosting has currently enabled on your website. Josh seconds this view:

If you have some sort of caching system as part of your hosting package already in place, and you're considering adding an additional caching plugin on top of it, it can cause conflicts between the two. I personally wouldn't go down that road. Either disable the one from your hosting provider and add a plugin but don’t use two.

The more, the merrier doesn't apply here. Actually, it should be: use one only that does the job at its best.

Question #4: Is it preferable to use the caching option provided by the hosting service or a caching plugin?

The caching service depends on the quality of the hosting service. A few notable ones - like SiteGround, DigitalOcean, Cloudways, WP Engine - provide extremely efficient and powerful caching features, which can be used without having to opt for any alternatives. Josh elaborates this point with respect to certain services:

Not all caching systems are created equal. I would always recommend that if your hosting provider has a system, use that first. And then, if it's not doing what it should do, look at changing your host to one where you can actually add your own caching system, or find a way to disable the inbuilt caching system. Personally, out of all the inbuilt caching systems I have used, WP Engine has always worked well. Their caching system is amazing and if you have the budget, go for it.

Wrapping up

Caching is vital for your website's performance because of the optimization that they bring along. Relying on caching plugins, even though seen as a common tactic, it's a pretty technical matter more than the average WordPress user realizes and wrong setups can provide you with (almost) no benefits.

Still, you could reach good improvements by combining good plugins and having them properly set up either by your in-house developers or a speed and performance optimization specialist. No matter what your preferences are, it's time to think about your website's speed because your customers have already been doing so for the past years!

This blog post features Josh Morley who is the founder of MarketingTheChange, a small digital agency that use its profits to support charities, non-profits and unfunded startups. He’s been designing & marketing websites for the past 4 years, with a focus on WordPress webdesign, online marketing and SEO, PPC, keyword research, link-building and lead acquisition for local business.

WordPress Speed Optimization ChecklistQuality: The Codeable Differene

  • Luke Cavanagh

    Most WordPress caching plugins fall over under real load, compared to Varnish or NGNIX caching.

    • Hi Luke,
      My piece is about just scratching the surface and let non-technical business owners get a better picture on caching plugins. Which is something, as WordPress users, you keep hearing a lot about.

      To your comment, the intended reader’s reaction would be: 🤔, which is no good. As I’d like to provide the maximum value here, I’d like to ask you a little thing: how about trying to translate/explain your comment like if you were talking to that nontechnical reader in person?

      • Luke Cavanagh

        Okay just saying WP Rocket will speed up your WordPress site, when a decent amount of traffic does come to your site, the site speed that you noticed in GTmetrix or Pingdom does not translate into keeping the site up and be a usable caching solution with a lot of users hitting your site at the same time. Which is why I said server-side (hosting) caching in the form of either NGNIX or Varnish will be better solutions for really being able to keep your WordPress site performing and keep it loading fast.

        • Luke Cavanagh

          Quick test, have say a WooCommerce store and use Load Impact test to hit the site with 500 virtual users with a WordPress cache plugin plugin (pick one they all work the same way) and then look at what the load and response time now is, they seem fine for a small amount of users, but as it ramps up it will fall over.

        • Josh Morley

          Thanks for your comments. I agree when you start getting into the realms of high traffic sites. Server-side caching is a must. However, working with over 350 clients on Codeable only about 5%-10% would require moving to a host with Varnish or NGNIX caching.

          Like Matteo said this post is only scratching the surface and very non-technical. Your idea might make a good follow up posts. ‘When Caching Plugins Are Not Enough’ :)