Caching is how fast WordPress sites stay fast. Without it, every visitor request triggers a full PHP execution cycle: WordPress boots, queries the database, builds the page, and sends the result. On a busy site that process runs thousands of times per hour. With caching, the completed result is stored and served directly, skipping the work entirely.
There are four main types of caching that apply to WordPress. Understanding what each one does explains why some speed improvements are dramatic and others barely register.
The Four Types of WordPress Caching
| Cache type | What it stores | Where it lives |
| Page cache | Complete HTML pages | Server disk or memory |
| Object cache | Database query results | Server memory (Redis / Memcached) |
| Browser cache | Static assets (images, CSS, JS) | Visitor’s browser |
| CDN cache | Static assets and sometimes full pages | Global edge network |
Page Cache: The Biggest Performance Gain
Page caching stores the completed HTML output of each WordPress page. When the next visitor requests that same page, the server returns the stored HTML directly instead of running PHP and querying the database again. This is the single most impactful caching layer for WordPress.
A non-cached WordPress page on typical shared hosting might take 400ms to 800ms to generate. The same page served from a warm page cache can respond in under 50ms. That difference shows up directly in TTFB and feeds into your Core Web Vitals scores.
On managed hosts like WP Engine, page caching is handled at the server level through EverCache. You do not need a caching plugin. On standard hosts, plugins like WP Rocket, W3 Total Cache, or LiteSpeed Cache handle this layer instead.
Page cache has an important limitation: it only works for pages that are the same for every visitor. Logged-in users, WooCommerce cart pages, and checkout pages cannot be cached because their content changes per user.
Object Cache: Reducing Database Load
WordPress queries its database constantly. Every time a page loads, WordPress runs dozens of queries to retrieve settings, post data, user permissions, and widget configurations. Many of those queries return identical results on every request.
Object caching stores the results of those database queries in server memory using Redis or Memcached. Repeated queries return the stored result from memory in microseconds instead of hitting the database again. On sites with complex plugins, membership systems, or large databases, object caching can dramatically reduce database load and improve performance for logged-in users who bypass page cache.
WP Engine includes Redis-based object caching as an add-on. On standard hosting, you need a plugin and a server that supports Redis or Memcached, which most shared hosts do not.
Browser Cache: Making Repeat Visits Faster
When a visitor loads your WordPress site, their browser downloads images, CSS files, JavaScript, and fonts. Browser caching tells the browser to keep those files stored locally for a set period — hours, days, or weeks.
On a repeat visit, the browser loads most of the page from its local cache rather than downloading everything again. This reduces page load time significantly for returning visitors and cuts the number of requests your server receives.
Browser caching is controlled by HTTP headers (Cache-Control and Expires) set either in your server configuration or by a caching plugin. WP Engine sets appropriate browser cache headers automatically. Most caching plugins handle this for standard hosts.
CDN Cache: Serving Assets Closer to Visitors
A CDN (Content Delivery Network) stores copies of your static assets — and sometimes full cached pages — on servers distributed across the world. When a visitor requests a file, the CDN serves it from the node closest to them geographically rather than from your origin server.
For a site hosted in a US data centre, a visitor in Germany loading images from your origin server adds 100ms to 200ms of latency just from the distance. A CDN with a European edge node eliminates most of that. For more on how CDNs work and whether your site needs one, the CDN explainer covers the specifics.
WP Engine includes Cloudflare CDN on all plans. On standard hosts, you add a CDN separately through Cloudflare’s free tier, BunnyCDN, or similar services.
How WP Engine Handles Caching
WP Engine’s EverCache system operates at the server level and handles page caching automatically for all sites. There is nothing to configure. Pages are cached on first load and served from the cache on subsequent requests, with intelligent cache invalidation when content is updated.
EverCache also includes a WooCommerce-specific layer that handles the caching exceptions required for store pages: product pages and category pages are cached normally, while cart, checkout, and account pages bypass cache correctly. For a detailed breakdown of how EverCache works, see What Is EverCache and Why Does It Matter for WordPress.
Because caching is managed at the server level, installing a third-party caching plugin on WP Engine is unnecessary and can cause conflicts. WP Engine explicitly advises against it.
Frequently Asked Questions
Do I need a caching plugin on WP Engine?
No. WP Engine’s EverCache system handles page caching at the server level and is more effective than plugin-based solutions. Installing a caching plugin on WP Engine can cause conflicts and is not recommended.
Why does my cached site still feel slow?
Page cache helps logged-out visitors on standard pages. If the slow experience is for logged-in users, WooCommerce checkout, or pages that bypass cache by design, the bottleneck is somewhere else: server resources, unoptimised database queries, heavy plugins, or slow third-party scripts. Object caching and database optimisation address the logged-in performance problem.
How do I clear the cache on WP Engine?
From the WP Engine dashboard, go to your site and click Flush Cache. This clears the EverCache page cache for all pages. You can also clear cache from within WordPress using the WP Engine toolbar at the top of the admin screen, or purge individual pages by URL.
Does caching work for WooCommerce?
Standard page caching works for product pages, category pages, and static content. Cart, checkout, and My Account pages cannot be cached because their content is unique per user. WP Engine’s EverCache handles these exceptions automatically without any configuration.
