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Building and maintaining your website is a complex undertaking. The website has to be intuitive, comprehensive, and mobile-responsive. It has …
Building and maintaining your website is a complex undertaking. The website has to be intuitive, comprehensive, and mobile-responsive. It has to be visual and dynamic enough to keep users interested. Yet, it also has to be fast.
Combining all of those elements would be impossible without a little thing called caching.
In many ways, website cache is the secret to the way the modern internet works. A small cog in a giant wheel that is nonetheless essential. But it can also become problematic.
Ever wonder why content you’ve updated on the backend doesn’t actually show up for end users? Blame caching. Caching is the most frequent cause of support queries for our clients, but with a few simple clicks balance can be restored.
So consider this your comprehensive guide to caching, why it’s essential for fast websites, how it works, and how to manage it on your WordPress website to help improve page load times and ensure a better experience for your users.
Caching as a concept has existed almost as long as the internet itself. In 1967, IBM released a new computer with a major improvement: it would be able to collect data on an intermediary ‘store’, allowing the system to bypass core processing for repeated tasks.
In his book IBM’s 360 and Early 370 Systems, IBM Journal editor Lyle Johnson who coined the term cache, compares the concept to the front desk of a library. It’s a temporary store for frequently used items that don’t have to go back on the bookshelf.
Anyone wanting to check out these items doesn’t have to wait the extra time it takes to seek them out. Because they’re so popular, they’re already available.
Or as Impact Media’s James puts it:
“You hit the gym daily, but don’t want to carry your trainers on your daily commute into London. So you take them in once and leave them in a locker. They are there when you need them and every now and then you need to clear out your locker (or wash your trainers) and website caching works in the same way. But less sweaty and smelly.”
It’s been more than 50 years since the term was coined, but this concept hasn’t changed.
Today, caching is a core part of how nearly any website operates. Those great graphics, animations, and embedded videos can only load as fast as you want because elements of the website are pre-stored on intermediary storage, either in the user’s browser or on a server, making them easier to retrieve.
TechTerms.com explains exactly what that means in practical terms for the user:
When you visit a webpage, the browser may cache the HTML, images, and any CSS or JavaScript files referenced by the page. When you browse through other pages on the site that use the same images, CSS or JavaScript, your browser will not have to re-download the files. Instead, the browser can simply load them from the cache, which is stored on your local hard drive.
The same is typically true when you go back to the website. Without caching, the fast load times that every marketer craves would be impossible to achieve.
Since Google introduced Core Web Vitals as a ranking signal, page speed has become a direct SEO factor, not just a user experience nicety. Metrics like Largest Contentful Paint (LCP) and Interaction to Next Paint (INP) are heavily influenced by how quickly cached assets are served, alongside Cumulative Layout Shift (CLS). A well-configured caching strategy is core to a strong technical SEO strategy.
Caching exists in almost every aspect of computing today. When it comes to your website, four distinct types of the process become especially relevant:
Every major browser, from Google Chrome to Mozilla Firefox, saves certain elements of each website visited to increase user-friendliness.
Well-built websites can communicate with users’ browsers when the content is outdated to clear the cache, and every user can manually clear their cache as well.
This is the type most relevant to WordPress owners. Think of it as similar to browser cache, except stored on the client side.
A cached version of your fully rendered HTML page is stored on your server, so when a new visitor arrives, the server can serve the cached copy instantly instead of rebuilding the page from scratch with every request. Because it’s controlled by the website, it’s a bit easier to flush when needed.
This operates further from the end user than those we’ve already covered, and stores the results of database queries or PHP operations on the server itself.
For WordPress sites with lots of dynamic content, WooCommerce shops, membership sites, large blogs, etc, object caching with tools like Redis can dramatically reduce database load and page generation time. It’s the most complex layer to configure, but the performance gains can be significant.
A Content Delivery Network (CDN), such as BunnyCDN, Cloudflare, or Amazon CloudFront, stores copies of your website’s static assets (images, CSS, JavaScript) across a global network of servers.
When a visitor loads your site, those assets are served from the server geographically closest to them, dramatically reducing latency.
CDN caching is increasingly essential for any website with an international or geographically dispersed audience, and many CDN providers also offer an added layer of DDoS protection and security. Services like Bunny and Cloudflare can be configured to work directly alongside your WordPress caching plugin.
Make no mistake, caching happens on every website because of just how important it is to the modern user experience. More specifically, its benefits revolve around site speed, server stability, and content availability.
As we’ve already hinted at, the biggest benefit of caching is site speed. If the browser or server already has what’s needed, it doesn’t have to request it again.
Research suggests that a loading a cached page can reduce HTML requests by more than 90%. In non-technical terms, that means your server only needs to generate a fraction of the data it would otherwise need to. It’s difficult to overstate the importance of that reduction.
Your website visitors, regardless of your industry, expect your website to load quickly. Google’s research has found that 50% of users will abandon a website if it takes more than 3 seconds to load. For mobile users, that threshold is even lower.
Fewer requests to your server, and less data needing to be downloaded each time, also improves the stability of your website.
Downtime can happen easily because of server overload. If you get that influx of web traffic you’ve been waiting for, you don’t want your site to crash because the server can’t handle the simultaneous requests. Caching isn’t a magical solution, but it significantly reduces the strain, as cached content is served without touching the database.
Should your server temporarily go down or experience high load, fully cached pages can still be delivered to users already browsing the site. This creates a more resilient, continuous experience even during unexpected outages.
With the benefits out of the way, let’s focus on the opposite end of the spectrum. Caching is essential for any modern website, but that doesn’t mean it’s without its faults.
We’ve already discussed the most obvious and common problem above. But it’s worth reiterating again. Perhaps the most frequent cache-related issue you’ll run into, is when you publish new content, but it just doesn’t seem to show up on the website’s front end.
Browser and page caches continue to serve the old content until they deem the new version more relevant. This can be anywhere from minutes to hours, depending on your configuration.
This matters most for time-sensitive updates: new pricing, a breaking announcement, a new job listing, or event information. What was supposed to be a timely update becomes a frustrating mess for site visitors.
When outdated content remains cached, because no expiry rule has told it to refresh, it can be just as damaging. Imagine a visitor finding outdated pricing, a former team member listed on your About page, or a sold-out product still showing as available.
A cache that simply stores old content forever, an uncontrolled cache in other words, can lead to this type of issue.
We won’t bore you with the details about header coding that tells your cache what to do. When you work with the right web development partner, they can take care of that, with a properly configured caching policy with sensible TTL (Time to Live) values prevents this. Still, it’s worth diving into the importance of telling browsers when to clear old caches.
TTL defines how long a cached item should be considered valid before the system fetches a fresh copy. Static assets like logos might have a TTL of 30 days; a dynamic pricing page might need a TTL of just a few hours.
This is a particularly common gotcha for WordPress sites. Caching should generally be disabled for logged-in users. If an admin, editor, or WooCommerce customer is served a cached page, they may see incorrect account data, stale basket contents, or miss personalised content entirely.
Most WordPress caching plugins handle this automatically, but it’s worth verifying in your plugin settings, especially on WooCommerce sites where cart, checkout, and account pages must always be served dynamically.
Caching and security don’t always go hand in hand. Banks and financial institutions, for example, never cache sensitive account or payment information, and for good reason. Cache poisoning attacks, where malicious actors inject harmful content into a cached response, are a real threat.
Best practice is to explicitly exclude sensitive pages (login pages, checkout, account pages, admin areas) from your caching rules. Work with your web developer to ensure these exclusions are correctly configured, and consider a CDN provider like Bunny or Cloudflare that offers built-in cache security features.
Every comprehensive website strategy has to include a caching component. That helps to build on the benefits and increase speed and stability, while minimising the potential problems that can occur as a result. Much of that strategy lies in the coding of the website itself.
First things first. The most controllable type of caching discussed above is website caching.
Server caching is more complex, while browser caching depends in large part on the user. You can influence both and gain influence if your website lives on a private server, but it’s typically a good idea to start with web caching in building out your policy.
The first step has nothing to do with coding. Instead, it simply involves going through your sitemap and determining where caching makes the most sense. High-traffic landing pages that don’t require a login tend to be the most natural fit.
Then, for each page, identify the specific elements worth caching:
The list can extend beyond these, but that tends to be a good starting point.
When in doubt, discuss with your web development partner, their experience with your particular setup is invaluable.
This is where it gets complicated. Through HTTP header tags, an experienced developer can set rules for each page. When content should be considered stale, what should never be cached, and how long different assets should remain valid. These Cache-Control headers work in conjunction with your caching plugin to give you precise control.
If you’re not an expert in coding, this can quickly become too complex to manage. Most page templates have pre-existing code already built in, so you might just want to check with your web developer to see if there are any custom rules you should be aware of, and what their recommendations are, as default configurations aren’t always optimal for your specific content mix.
For most WordPress websites, a dedicated caching plugin is the most accessible way to implement and manage caching. If your website is supported and managed by your developer they will likely have one they prefer to use. Here are some of the most widely used ones:
Always check that your chosen plugin is compatible with your theme, page builder, and hosting environment before activating it on a live site. A good web development/support agency will always test new plugins on a staging version of your site first.
As we’ve established in the caching challenges above, even a good strategy with these header tags may not be enough. You don’t always know ahead of time when new content drives the older variation out of business. Fortunately, WordPress makes flushing all existing caches relatively simple.
Some plugins can help. Other builds have this option built-in to the actual solution. Talk to your web developer about what exactly it takes, and of course, clearing your cache on your browser could be a simple and great step to take care of the issue.
Be careful though, flushing the cache too often can cause those slow load times and potential server instabilities discussed above.
Make sure you have a good reason to take this step, such as new core content that absolutely cannot wait to cycle through the ‘regular’ process.
Caching is a relatively small component of the larger website build, but its importance is outsized. A well-configured caching layer touches your site’s speed, stability, SEO performance, and security simultaneously.
Understanding what you’re dealing with is the first essential step. Knowing how to manage it comes right after. The key elements to get right are: choosing the right caching plugin for your setup, configuring TTL and cache exclusions correctly, ensuring logged-in users and sensitive pages bypass the cache, and layering in a CDN if you have an international audience or traffic spikes to handle.
When in doubt, bring it up with your web agency. That helps you better manage your website, and make crucial improvements in the future.
You don’t have to be a developer to leverage caching effectively. You just have to work with the right development partner, and understand enough about the topic to ask the right questions.
Reach out to Impact Media with any questions on the topic, and for help in creating a caching solution for your WordPress website that improves your website speed without compromising its stability or quality.
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