The WP Rocket plugin is a powerful tool for optimizing the load times of your WordPress site. Many of its features are one-click and done, but it does have limitations. Some optimizations still need to be done by hand to pass certain Core Web Vital metrics.
Optimizing with WP Rocket
WP Rocket is a premium plugin for WordPress that helps improve website performance by caching static files, optimizing images, and implementing various speed-enhancing features. With WP Rocket, you can enable and fine-tune features as needed to achieve significant performance improvements.
Critical Path CSS
Critical Path CSS (CPCSS) is a technique used to improve web page loading speed by prioritizing the delivery of CSS styles required to render the visible content above the fold. By identifying and delivering these essential styles quickly, this optimization ensures faster perceived page load times and better user experience.
Minification
WP Rocket minifies your website’s HTML, CSS, and JavaScript files by removing unnecessary characters and whitespace without altering their functionality. Minification reduces file sizes and speeds up loading times by optimizing code delivery to visitors’ browsers.
Lazy Loading
Lazy loading is a technique that defers the loading of non-essential resources (such as images, iframes, and videos) until they are needed. WP Rocket’s lazy loading feature ensures that only the visible content is loaded initially, improving perceived page load speed and reducing the number of HTTP requests.
DNS Prefetching and Preloading
WP Rocket allows you to prefetch and preload DNS requests and key resources, such as external fonts and third-party scripts. By resolving DNS queries and loading essential resources in advance, you can reduce latency and improve page load times, leading to a better PageSpeed Insights score.
Optimizations Outside of WP Rocket
Some optimizations are out of reach for WP Rocket and need a developer’s attention.
Cumulative Layout Shift
Cumulative Layout Shift (or “CLS”) is a measure of how much elements shift around during load time. Unexpected layout shifts can negatively impact the user experience in various ways, such as causing readers to lose their place if the text suddenly moves, or leading them to click the wrong link or button. In some instances, this can result in significant consequences.
CLS can be caused by many issues, such as images or videos without width & height values defined or dynamic elements like carousels that change dimensions as the page loads. Many of these issues cannot be fixed by a plugin, but instead need a developer to assess the underlying cause(es) of the CLS and put a remedy in place.
Image Compression Optimization
WP Rocket doesn’t feature the ability to compress your images in next-generations formats like WebP and AVIF. This step is important to optimize the delivery of images and to satisfy Google PageSpeed Insights. This can be handled with a separate plugin or through a third-party service that provides this functionality, like CloudFlare’s Polish.
Leveraging CDNs
A CDN is important because it speeds up website loading times, improves reliability by distributing traffic, enhances security, and reduces server load by caching content across a global network of servers. WP Rocket does offer this as an add-on service, but your existing hosting service may already offer CDN functionality (for example WP Engine).
Many open source projects are also available on free CDNs like jsDelivr and cdnjs. This would require changes to your theme files to use these sources.