Greetings, Wordpress Wizard

What is object cache in Wordpress?

Object cache is a set of functions, that allows theme and plugin developers to store different data using unique keys in a usually in-memory systems, like Redis or Memcached for faster access. Unlike database, to get information out of the object cache you need to know specific key, that you are looking for, but at the same time access to stored data is much more faster.

Wordpress offer natively offers functions for dealing with object cache, but unless you have a specific plugin, that connects to external cache daemon to store or retrieve data - all object cache will be stored inside running PHP process and data will be lost after request handling. Basically it means, that on a new request - object cache will be empty. And that's why you need external cache daemon and a plugin, that will actually work with it.

Since object cache itself is not bound to specific storage - Wordpress plugin repository offer various plugins, that utilize different methods for data storage - redis object cache, memcached, opcache and even file-based caching (it is hard to think, when this might be a good idea to have, but technology itself allows us to do it).

Object Cache on Shared Hosting

If you're running WordPress on shared hosting and experiencing performance issues, you might be tempted to enable object caching with Redis or Memcached. However, for most beginners and intermediate users, this approach requires careful consideration.

Security Concerns Worth Noting

On typical shared hosting environments, Redis and Memcached often lack proper user authentication and data isolation between accounts. Unless your hosting provider specifically offers these services through dedicated containers (like those available in the "Enhance" control panel), your cached data could potentially be accessed or modified by other users on the same server.

When Performance Lags Despite Good Hardware

Object caching shines in specific scenarios, particularly with themes and plugins that perform complex calculations. For example, WooCommerce stores with variable products can see significant speed improvements when the lowest price calculations are cached rather than repeatedly processed.

Better Alternatives to Consider

Try Docket Cache - If you don't have access to Redis or Memcached but want object caching benefits, this plugin stores cache data in files while providing similar functionality.

Object caching is a powerful tool when used correctly and in the right environment. For shared hosting users, it's often better to focus on finding a hosting provider with better performance characteristics unless you're experiencing specific bottlenecks that only object caching can address. If your CPU benchmarks look good but pages still load slowly, and your plugins/themes support object caching, then it might be worth exploring—preferably on VPS or dedicated hosting where security concerns are minimized.

Your questions, comments and suggestions are kindly welcome at info@wpbenchmark.io.