Page Caching: Redis Full Page Cache vs. NGINX FastCGI Caching

Page caching stores the finished HTML of a page so the server can hand it to the next visitor without running PHP and database queries again. It is one of the easiest ways to cut load time and server load at once.

This guide compares two server-level options: Redis Full-Page Cache and NGINX FastCGI Caching. Both speed up your site a lot. The differences are in where the cache lives, how it is managed, and what suits your traffic. At the end, we cover the third option most WordPress sites now use: a caching plugin.

Web Page Caching: What Does It Mean?

Imagine you’re reading a book and you keep flipping back and forth between pages to keep track of information. Caching is like putting sticky notes on the pages you keep going back to, so you don’t have to search for them every time.

Your browser does this with images, CSS and scripts, which is browser caching. Page caching does the same thing on the server: once WordPress has built a page, a copy of the HTML is kept in a cache, and the next request for that page gets the copy instead of a fresh build.

In short, page caching speeds up server response times by reusing work the server has already done.

How Does Page Caching Work: Two Techniques Explored

There are two common server-level page caching techniques. Both improve performance significantly; here is how each works so you can decide which suits your WordPress website:

Redis Full-Page Caching: Redis (Remote Dictionary Server) is an open-source, in-memory data store that is extremely fast. Redis Full-Page Caching keeps the complete HTML output of each page in memory.

NGINX FastCGI Caching: NGINX is a popular, high-performing web server. With FastCGI caching, NGINX stores the response PHP produced for a request (usually the full HTML page) on disk, and serves later requests for that URL directly, without involving PHP or WordPress at all.

Understanding these techniques helps website owners choose the best caching method for their websites and their needs, improving website speed and user experience.

Redis Full-Page Cache vs NGINX FastCGI Caching: Which One Is Best for You?

So, which one of these two should you use for your WordPress website? Let’s break down these methods and see how they stack up against each other.

🎯 Definition and Functionality

Redis Full-Page Cache: Full-Page Cache stores entire web pages in a cache, enabling quick retrieval and delivery to users upon request.

NGINX FastCGI Caching: NGINX FastCGI Caching caches the responses PHP returns for each request and serves them at the web server level.

🎯 Working Mechanism

Redis Full-Page Cache:

• Upon a user’s request, the server checks if the requested page is in the cache.
• If cached, the server serves the page directly from the cache, bypassing the need to regenerate it.
• If not cached, the server generates the page, saves it in the cache, and then delivers it to the user.

NGINX FastCGI Caching:

• NGINX examines incoming requests to determine if a cached response exists.
• If a cached response is found, NGINX serves it directly to the user.
• If no cached response is available, NGINX forwards the request to PHP-FPM, caches the response, and then delivers it to the user.

🎯 Content Suitability

Redis Full-Page Cache:

• Best suited for websites with predominantly static content, where pages don’t change frequently.
• Ideal for blogs, informational websites, and eCommerce product pages with stable content.

NGINX FastCGI Caching:

• Well-suited for websites with dynamic content that changes frequently.
• Suitable for content-heavy platforms, dynamic web applications, and sites with personalized user experiences.

🎯 Performance Benefits

Redis Full-Page Cache:

• Offers faster load times as entire pages are cached and readily available for delivery.
• Reduces server load by serving cached pages, thereby enhancing server performance and scalability.

NGINX FastCGI Caching:

• Provides granular caching capabilities, allowing specific responses to be cached for optimized performance.
• Improves server efficiency by offloading processing tasks to NGINX, resulting in reduced response times and enhanced scalability.

🎯 Implementation Complexity

Redis Full-Page Cache:

• Relatively straightforward to implement and configure, making it suitable for users with limited technical expertise.
• Requires minimal setup and maintenance, making it an accessible caching solution for beginners.

NGINX FastCGI Caching:

• May involve more intricate setup and configuration compared to Full-Page Cache.
• Requires familiarity with NGINX configuration settings and server administration for effective implementation.

🎯 Storage Requirements

Redis Full-Page Cache:

• Requires sufficient storage space to accommodate cached web pages.
• Storage capacity needs to be considered based on the size and frequency of page caching.

NGINX FastCGI Caching:

• Utilizes disk space for caching specific responses, which may vary depending on the volume and size of cached content.
• Storage requirements should be assessed to ensure optimal caching performance without exhausting available disk space.

Considering the factors above, the two techniques are neck-and-neck. Either one makes your website load significantly faster than no caching at all.

How Page Caching Works in xCloud

xCloud offers two server-level caching layers you can switch on per site: page caching and object caching.

For page caching, xCloud uses NGINX FastCGI caching, which keeps ready-made pages on the server for instant delivery.

Now, onto object caching. This is all about saving specific pieces of info from the website’s database, like menus or post details. Instead of digging through the database every time someone asks for this info, we’ve already got it saved and ready to go. For this job, xCloud uses Redis Object Caching, which is different from Redis Full-Page Caching: it stores query results, not whole pages. Read more in our guide to advanced Redis object caching for WordPress.

Note: Object caching entails the storage of database query outcomes, enabling subsequent retrieval from the cache rather than reiterative querying of the database when the same result is required.

The Plugin-Level Option: xSpeed Cache on New xCloud Sites

Server-level caching is not the only route. On WordPress, a caching plugin can handle page caching itself, along with object caching and browser caching, from inside wp-admin.

New WordPress sites on xCloud get xSpeed Cache. WPDeveloper, the team behind xCloud, builds it, and it is tightly integrated with the xCloud dashboard. It is switched on automatically during site creation, marked Recommended. The free plan covers page caching, object caching, browser caching, the preloader, minification and lazy loading, and a three-step Setup Wizard gets you to a fast baseline in about two minutes. WooCommerce cart, checkout and account pages are excluded from caching automatically.

When xSpeed Cache is on, xCloud keeps its own Full Page Caching and Redis Object Caching toggles off for that site. xSpeed already covers page and object caching, and running two page caches or two object caches side by side would conflict. On OpenLiteSpeed servers, xSpeed manages its own server rules. You can set it up with our guide to configuring xSpeed Cache settings in xCloud.

The FastCGI and Redis options above are still there for sites that don’t use xSpeed Cache. If you host elsewhere, you can get the same page caching plugin for WordPress free from WordPress.org; it runs on NGINX, Apache, LiteSpeed or any standard PHP host.

Choose the Best Page Caching Technique for Your Site

Redis Full-Page Cache and NGINX FastCGI Cache both cut load time and server load. Pick FastCGI if you want the cache at the web server level with nothing to manage in WordPress, or Redis if you prefer an in-memory store. On a new xCloud WordPress site, the simplest answer is to keep xSpeed Cache on and let it handle page, object and browser caching in one place.

Whichever you choose, remember to clear your website cache after major changes, and consider edge page caching to serve cached pages closer to your visitors.

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Frequently asked questions

What is the difference between Redis full page cache and NGINX FastCGI caching?

Both store the finished HTML of a page so it can be served without rebuilding it. Redis full page cache keeps that HTML in memory, while NGINX FastCGI caching stores it on disk and serves it straight from the web server before PHP runs. In practice, both make cached pages load far faster than uncached ones.

Is object caching the same as page caching?

No. Page caching stores whole pages, while object caching stores the results of database queries so dynamic pages like carts and dashboards build faster. Most WordPress sites benefit from both.

Which caching plugin should I use on WordPress?

Use one plugin that covers page, object and browser caching, so you don’t stack conflicting layers. New WordPress sites on xCloud come with xSpeed Cache installed and switched on, and it is free on WordPress.org for sites hosted elsewhere.

Can I use xCloud’s FastCGI cache and xSpeed Cache at the same time?

No, and you don’t need to. When xSpeed Cache is on, xCloud keeps its own Full Page Caching and Redis Object Caching toggles off for that site, because xSpeed already covers page and object caching and running both would conflict.