For large WordPress websites, caching becomes critical for site performance and a good visitor experience. The performance also affects search engine results and Google PageRank. Here’s a rundown of the basics of WordPress caching.
What is caching?
Caching is the use of RAM – the fastest memory available on your server – to store pages so they load much faster than retrieving them from the web server’s disk storage. Cached site components are snapshots of your WordPress pages, posts, and other items such as CSS and JavaScript. Normally, when a visitor requests a page or a post, WordPress must request that page or post – and all their components – from the WordPress database living on your web server’s hard disk. It must then wait for your server to respond before it can send the result to the visitor’s browser.
On large sites with lots of visitors, the difference between not caching and caching is measured in seconds. In general, web pages should load in less than 2 seconds. Uncached pages on large sites can take 5 seconds or more – long enough for many impatient users to go elsewhere.
While modern hard disks are very fast, they’re far slower than the RAM on your web server. Caching simply stores frequently accessed pages and posts in RAM, so WordPress looks for them in RAM first – no database queries required. Caching reduces server load and improves overall site performance.
What caching does for you
Caching provides several benefits to you and your site visitors:
- Pages load a lot faster, enhancing your site visitors’ experience
- Caching reduces the load on your web server so it responds faster to visitor requests for pages and posts
- Faster-loading sites typically rank better in search engine results
- For high-traffic sites, caching helps you conserve valuable bandwidth
The best caching plugins not only handle basic page caching, but they minify (reduce the size of) HTML, CSS, and JavaScript. HostPapa recommends the W3 Total Cache plugin for your WordPress caching needs.
Browser caching
Web browsers like Chrome, Firefox, Safari, and Microsoft Edge use memory on your computer to store data for pages you frequently access. Browser cache “remembers” the resources called by frequently accessed web pages to help those pages load faster when you visit. You can use the .htaccess file for your WordPress site to tell a user’s browser how to cache the pages on your site.
Web server caching
Web server caching is especially important for high-traffic websites. Plugins for your WordPress server cache a variety of data, including:
- HTML pages
- CSS and JavaScript
- Database queries
- Various code objects
- PHP opcodes
The place to begin with web server caching is to use a plugin such as W3 Total Cache Plugin for WordPress. That plugin alone will substantially improve performance.
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