Category: Optimization

The WordPress REST API returns full post objects by default — including 40+ fields, embedded author objects, and taxonomy arrays — even when the client only needs the title and permalink. The _fields parameter enables sparse fieldsets to reduce payload size by 80–90%, and combining sparse fieldsets with HTTP caching headers and a Redis-backed response…

WordPress 5.8+ generates WebP versions of uploaded images automatically (when the GD or Imagick extension supports it), and WordPress 6.5 added experimental AVIF support. A complete image optimisation pipeline combines format generation, quality tuning, responsive srcset attribute output, and a <picture> element fallback for maximum browser compatibility and minimum file size.

Render-blocking stylesheets are one of the most common LCP and FCP bottlenecks on WordPress sites. The solution — extracting the CSS required to render above-the-fold content (“critical CSS”) and inlining it in <head> while loading the full stylesheet asynchronously — eliminates the render-blocking request entirely. The challenge is automating extraction and keeping the critical CSS…

WordPress’s object cache API supports cache groups — named namespaces that let you flush a logical set of entries atomically without clearing the entire cache. Combined with a persistent backend (Redis or Memcached), groups are the right tool for caching expensive queries while ensuring stale data is never served after content changes.

Full-page caching stores the complete HTML output of a WordPress page so subsequent requests are served without executing PHP or querying MySQL. It is the most impactful single performance optimisation for most WordPress sites — the difference between 10ms and 500ms page response time.

WordPress object caching with an external backend — Redis or Memcached — eliminates redundant database queries by storing the results of wp_cache_get() calls in memory. Choosing between Redis and Memcached depends on your persistence, data-structure, and cluster requirements.

Removing whitespace from HTML output and inlining above-the-fold CSS are two of the highest-ROI performance techniques for WordPress — they reduce Time to First Byte payload and eliminate render-blocking stylesheets in a single request.

WordPress has three distinct caching layers that operate at different granularities and serve different performance goals — understanding which layer to use for a given problem determines whether you achieve a 5% improvement or a 10x improvement. The WordPress Object Cache (wp_cache_set(), wp_cache_get()) is an in-memory runtime cache that stores arbitrary PHP values for the…

Resource hints are HTML <link> elements that instruct the browser to perform network actions — DNS lookups, TCP connections, or resource fetches — before those resources are discovered in the normal parsing flow, eliminating the sequential discovery waterfall that slows page rendering. Four hint types serve different purposes: rel="preconnect" establishes the TCP+TLS connection to a…