WordPress is an amazing tool for publishing a website tied into a relational database. In order to make a WordPress website perform as fast as possible, Pressable uses a number of cache types. Understanding how Pressable accelerates your website with caching will help you design better websites that perform the best for your users.
Caching
Every time a visitor lands on your WordPress website, WordPress has to fetch information from your MySQL database. If you have a lot of functionality and assets on your website, that’s a lot of information to fetch, so your load time increases.
At Pressable, there are a few types of caching occurring: page caching (Batcache, advanced-cache.php, via Memcache), database query caching (WordPress Object Cache, extended by object-cache.php via Memcache), OPCache (PHP Code), and page + static asset caching at the edge (Edge Cache, which replaces the Legacy CDN).
Page and Query Caching
Both page caching and database query caching use WordPress’ Object Cache. Page and database query caching (for queries that use the WordPress Object Cache class) are always on at Pressable. However, you can exclude certain pages from Batcache.
Edge Cache (Static Asset Caching)
Pressable provides Edge Cache across all plans, a free performance feature that allows your WordPress sites to leverage our global network of edge servers to deliver both page and static asset cache.
Edge Cache replaces the Legacy CDN by combining static asset delivery (like a traditional CDN) with full-page caching at the edge. This provides significant performance improvements, especially in terms of your site’s TTFB, by serving content directly from the closest edge server available to your visitors.
Edge Cache already acts as a CDN, adding an additional CDN (such as Jetpack CDN or another third-party provider) may introduce extra external HTTP requests and reduce performance. We recommend relying on Edge Cache alone unless you test thoroughly and confirm benefits from layering another CDN.
OPCache (PHP Code)
Since PHP version 5.5, OPCache has been available for storing a precompiled script bytecode in the memory. This reduces server load in subsequent calls for a PHP file by having it ready to go as soon as it is called.