The Complete Guide to Clearing Your WordPress Cache

Do you want lightning fast load times for your WordPress site? Caching is one of the best ways to accelerate your site‘s performance. But to serve the latest content, you need to know when and how to clear your WordPress cache properly.

In this detailed guide, we‘ll cover everything you need to master WordPress caching and cache management.

Why Caching is Essential for WordPress Performance

Before we dive into clearing your WordPress cache, let‘s understand why caching is so important for WordPress sites in the first place.

Put simply, caching stores copies of your WordPress pages and posts so they can be served quickly to visitors. Instead of rendering the page from the database on each request, a cached static version is sent.

This eliminates database queries, PHP execution and HTML generation on each page load.

As a result, cached pages load incredibly fast. Just how much faster?

As per Cloudflare, enabling caching can improve WordPress page load times by 50-80% or more.

Some key website performance metrics improve significantly with caching:

Metric	Improvement
Page load time	50-80% faster
Server response time	65% reduction
Bandwidth utilization	25-50% decrease
Traffic capacity	2x or 3x more visitors

Caching not only provides a faster experience to your users, but also reduces strain on your web server by minimizing resource intensive operations.

Your server can handle 2-3x more traffic without slowing down when caching is implemented. This translates into huge hosting cost savings, especially during traffic spikes.

Common WordPress Caching Techniques and Tools

There are a number of caching techniques that can be utilized to accelerate WordPress sites:

Page Caching – Entire HTML pages are cached. This is the most effective caching method. Plugins like WP Rocket use page caching.
Object Caching – Caching database queries, external API requests and code fragments. Tools like Memcached enable object caching.
Database Caching – WordPress database queries are cached for faster execution. Query Monitor and WP DB Abstraction plugin can cache database requests.
Browser Caching – Browsers cache static assets like images, CSS and JS files locally so they don‘t have to be downloaded again. Leveraged by caching plugins.
CDN Caching – Content is cached in data centers around the world so it‘s closer to visitors. Services like Cloudflare and BunnyCDN provide CDN caching.
Reverse Proxy Caching – A proxy server caches sites and serves cached pages to visitors. Varnish and Nginx can be used.
Lazy Loading – Images below the fold are loaded only when the user scrolls down. Cuts down initial page weight.
Minification – HTML, CSS and JS files are minified by removing whitespace, comments etc to reduce their size.

Now let‘s specifically see how page caching works and how it can be implemented in WordPress.

How Page Caching Works in WordPress

Page caching is the most effective caching technique for WordPress sites. This is how it works:

When a user requests a page on your site, the WordPress page is generated dynamically by executing PHP code, running database queries and compiling HTML. This raw HTML page is served to the user.
The page HTML is also cached by the caching plugin‘s server-side cache. This cached version is served for subsequent requests to this page.
The cache is maintained for a configured duration or until manually cleared. New requests are served from the cache instead of generating the page from scratch.
When the cache expires or is cleared, the next request generates a fresh cache. The cycle continues.

Page caching plugins for WordPress typically utilize server-side caching with solutions like Redis or Memcached.

Some popular page caching plugins include:

WP Rocket
WP Fastest Cache
W3 Total Cache
LiteSpeed Cache
Swift Performance

These plugins generate cached static HTML files for your WordPress pages and posts. Most also minify HTML, CSS and JS automatically for added performance gains.

Now that you understand why caching is so important for WordPress and how page caching works, let‘s get into the core focus of this guide – when and how to clear your WordPress cache.

When Should You Clear Your WordPress Cache?

Caching has its benefits, but also a downside. Cached pages continue to be served until the cache is cleared manually or expires automatically.

This means your visitors may see outdated, stale content until the cache is purged.

So when should you clear your WordPress cache? Here are the most common scenarios:

1. Publishing New Content

Whenever you publish a new post, page, custom post type entry or WooCommerce product, you must clear your cache. This ensures visitors see the latest content on your site, not an outdated cached version.

2. Updating Existing Content

Making updates to existing pages and posts also requires flushing the cache. This ensures your changes are immediately reflected to visitors.

3. Switching Themes

Activating a new WordPress theme or editing your current theme‘s template files requires cache clearing. Without this, visitors may still see cached versions of old theme.

4. Installing or Updating Plugins

Plugin changes need to be reflected instantly to users. Added functionality, new features etc won‘t work until cache is refreshed.

5. Modifying Site Design

Updates to your site‘s design – fonts, colors, layout etc necessitate cache purging so visitors see the latest styles.

6. Fixing Broken Links/Images

Fix cached broken links and images by forcing regeneration of updated pages with accurate links/images.

7. Site Migrations

Caches referencing your old domain name can cause issues after migrating to a new domain. Flushing them is important.

8. Resolve Plugin Conflicts

Outdated cached pages can cause conflicts after plugin updates. Clearing them resolves such issues.

9. Fix Common WordPress Errors

Mysterious WordPress errors and bugs often disappear simply by clearing your cache. Its worth trying this first.

10. Periodic Cache Flushing

It‘s a good practice to periodically clear your entire cache every few weeks or months. This removes stale pages and keeps things fresh.

How Often Should You Clear Cache?

This depends on factors like how frequently your site content changes and your traffic levels.

Low traffic sites – Once a week
Medium traffic sites – Twice a week
High traffic sites – Thrice a week
Very high traffic sites – Daily
Ecommerce sites – Every 1-2 days. More often during sales.

Periodic cache flushing keeps things optimal by serving fresh content to visitors.

How to Clear Your WordPress Cache?

Let‘s now see how to actually purge your WordPress cache using some of the most popular caching plugins:

1. Clearing Cache in WP Rocket

WP Rocket is one of the top premium WordPress caching plugins. Here‘s how to clear WP Rocket‘s cache:

Login to your WordPress admin area and go to Settings > WP Rocket.
On the WP Rocket settings page, click on the Clear Cache button.
By default, this will purge all cached files. You can also selectively clear page, post or category cache if needed.

2. Clearing Cache in WP Fastest Cache

WP Fastest Cache is a free caching plugin trusted by over 3 million WordPress sites. To empty its cache:

Look for the WP Fastest Cache button on your WordPress admin bar.
Click and select Delete Cache from the dropdown menu.
This will delete the entire cache. You can also choose to clear cache for just the current page.

3. Clearing Cache in W3 Total Cache

W3 Total Cache is a customizable caching plugin from the W3 Edge team. To reset its cache:

In your WordPress dashboard, go to Performance > Purge.
Click on Purge All to empty the entire cache.
You can also selectively purge page, post or category cache as needed.

4. Clearing Cache in WP Super Cache

WP Super Cache is an easy to use, open source WordPress caching plugin. To purge its cache:

Go to the plugin‘s settings page.
Click on the Delete Cache button.
This will delete the entire cache. You can also clear cache for a specific page under Cache Contents.

5. Clearing Cache in Swift Performance

Swift Performance is a fast WordPress caching and optimization plugin. To clear its cache:

Go to Settings > Swift Performance in your dashboard.
Under the Cache tab, click on the Clear Cache button.
Optionally, you can also clear page specific cached files from the Cache Contents section.

Pro Tips for Clearing Your WordPress Cache

Here are some pro tips to keep in mind when clearing your WordPress cache:

After clearing server cache, preview site as a visitor to verify changes are reflected.
Selectively clear page/post cache if only some content is updated. No need to purge everything.
Consider a caching plugin that can auto-purge cache on content publication like WP Rocket.
Purge CDN and browser cache too for changes to take full effect.
Avoid clearing server cache too frequently on huge sites as it can temporarily slow things down.
Schedule weekly or monthly cron jobs to handle recurring cache flushing.
Some plugins like WP Rocket allow clearing cache on a per-user basis for granular control.
Check your caching plugin‘s documentation for any specific cache invalidation recommendations.
Complement server caching with Redis object caching for maximum WordPress performance.

Caching Plugins Comparison

While we‘ve covered the most popular options, there are several other WordPress caching plugins available. Here‘s a quick comparison table highlighting some key features offered by various solutions:

Plugin	Type	Key Features	Price
WP Rocket	Page caching	Cache preloading, Cache purges on content updates	$49+/year
WP Fastest Cache	Page caching	Browser caching, Multisite network support	Free
W3 Total Cache	Page caching	Fragment caching, Database caching	Free – $199+/year
Swift Performance	Page caching	Lazy loading images, Automatic cache management	$29+/year
LiteSpeed Cache	Page caching	Cache tag control, WooCommerce support	Free – $129/year
Comet Cache	Page caching	Cache 302 redirects, WebP image support	Free – $129/year
Hyper Cache	Page caching	HTTP/2 support, RSS feed caching	$49+/year
WP Redis	Object caching	Persistent caching, Native Redis integration	Free – $299+/year
Memcached Redux	Object caching	Automatic purging, Object cache offloading	$99+/year
Query Monitor	DB caching	Database debugging, Query performance monitoring	Free

Caching Challenges with Multi-Site WordPress Networks

Caching needs some special considerations when running a multi-site WordPress network:

Don‘t use network-wide full page cache as it creates conflicts across sites. Use object caching instead.
Place cache server close to the database server to minimize latency.
Add cache server rules to purge cache for specific sites only on content updates.
Use a dedicated memcache server per multisite instance for best performance.
Cache pages for logged-in users separate from anonymous traffic for greater control.
Limit number of sites using a single Redis cache cluster to under 80 for optimal performance.
Increase RAM on cache server to improve hit rate and minimize eviction of popular content.

Ecommerce Caching Tips and Best Practices

Ecommerce stores need strategic cache invalidation around key events for optimal revenue:

New product launches – Clear cache to allow customers to immediately view and purchase new products.
Cart/checkout flow updates – Any changes to cart or checkout funnels necessitate cache flush so users have smooth experience completing purchases.
Stock status changes – As products go out-of-stock or come back in-stock, clear cache to reflect real-time availability to shoppers.
Price changes – When product prices change during sales and promotions, cache must be purged frequently so customers get accurate pricing.
Personalization – segment cache by customer groups to serve personalized content. Signed in users can receive cache separate from anonymous traffic.
High load events – Preload cache before big sales, new product launches, holidays etc so server can handle spike in traffic.

How Reverse Proxy Caching Works with WordPress

Many sites use a reverse proxy cache like Varnish or Nginx Proxy Cache to cache WordPress pages:

Reverse proxy caching architecture — Reverse Proxy Caching with WordPress – Image via Kinsta

This is how reverse proxy caching works:

User requests page from WordPress site.
The reverse proxy checks if this page is cached.
If cached, the page is served from the proxy cache.
If not cached, the request is forwarded to the origin WordPress server.
WordPress generates the dynamic page and returns it to the proxy server.
The proxy caches the page and serves it to the user.
The cache remains valid until expiry or manual invalidation.

So when using a reverse proxy cache, you‘ll need to purge its cache instead of WordPress‘ cache when new content is published.

Varnish provides a CLI tool varnishadm to purge cache. Nginx has various cache purge modules. Most reverse proxies also support cache tags or bans to target invalidation.

Wrapping Up

Caching is a WordPress performance booster but requires smart cache invalidation for visitors to see fresh content. Use this guide to learn:

Why caching is essential for fast WordPress performance
Common WordPress caching techniques
When you should clear your WordPress cache
How to empty cache in popular WordPress plugins
Cache management pro tips and best practices

With the right caching strategy coupled with occasional strategic cache clearing, you can take your WordPress site‘s speed and performance to the next level.