Why does WordPress Health Check tell me to use a persisent object cache?

It's possible that your WordPress website's Health Check is suggesting that you make use of a persistent object cache - but what does that actually mean? In this guide, we'll explain what Object Caching is, and which platforms it can be used on with 20i - and the benefits of doing so.

Users with Managed Hosting or a Cloud Server can take advantage of Redis to enable object caching on their WordPress websites. 

Please note that object caching requires an additionally managed service such as Redis and as such is not available on the shared hosting platform (Linux/WordPress Optimised/Windows).

WordPress Object Cache

In the context of WordPress, an object cache is an additional component to the WordPress infrastructure designed to improve the performance and speed of a WordPress site by reducing the need to repeatedly retrieve data from the database.

It acts as a temporary storage mechanism that stores commonly used and frequently accessed data, such as database query results, API responses, and other PHP objects, in memory for quick retrieval. Here's how it works and the benefits it provides.

How Object Cache Works in WordPress

1. Data Storage

When a WordPress website loads a page or performs various operations, it often needs to query the database to fetch data like post content, user information, or options stored in the database.

2. Caching Data

Instead of querying the database every time the same data is required, an object cache stores this data in memory. The data is stored in a key-value format, making it easy to retrieve.

3. Faster Retrieval

When a specific piece of data is needed again, WordPress first checks the object cache. If the data is found there, it can be retrieved much faster from memory than by querying the database, which significantly speeds up the website's performance.

4. Expiration and Invalidation

Object cache systems typically allow you to set an expiration time for cached data, ensuring that it remains up-to-date. When data is modified or updated in the database, the object cache should also be updated or invalidated to reflect these changes.

Benefits of Object Caching in WordPress

Improved Website Speed

One of the most significant benefits is improved website speed. By reducing the number of database queries, pages load faster, leading to a better user experience.

Reduced Server Load

Fewer database queries mean less strain on the server. This is particularly advantageous for websites with high traffic, as it can help prevent server overload and slowdowns.

Better Scalability

Object caching is an essential tool for scaling WordPress websites. As traffic increases, the object cache can help handle more requests efficiently.

Optimized Database Performance

With common queries cached in memory, the database is less frequently accessed for the same data, reducing its load and improving overall database performance.

Plugin and Theme Performance

It can also enhance the performance of WordPress plugins and themes that rely on frequently accessed data, as these can benefit from faster data retrieval.

Reduced Latency

Object caching reduces the latency in serving web pages, which can be especially important for e-commerce websites and content-heavy blogs.

To implement object caching in WordPress, you'll need Managed Hosting or a Cloud Server, along with a compatible plugin such as Redis Object Cache.

These tools help store and manage cached data efficiently, making your WordPress site faster and more responsive, ultimately improving the user experience.