Even well-optimized WordPress sites hit snags when visitors jump between pages – those navigation delays add up and drag down Core Web Vitals.
Speculation Rules are the latest leap forward from old-school prefetching, giving browsers smart instructions to preload or even prerender pages before users click.
This means WordPress sites with heavy content and predictable navigation paths get a speed boost that older techniques can’t match; pages appear faster and smoother.
To get the most out of speculation rules, a strong hosting setup (like BigScoots!) with advanced caching and CDN capabilities is key. When paired with infrastructure built for performance and reliability, speculative loading can deliver near-instant page transitions and a noticeably better user experience.
In this guide, you’ll learn how speculative loading works and why it’s revolutionizing page speed. We’ll walk through the differences between prefetching and prerendering, help you choose the right approach for your WordPress site, and show you how to implement the Speculation Rules API effectively. You’ll also discover how the right hosting infrastructure can amplify these benefits and turn faster page loads into your site’s competitive advantage.
What is Speculative loading, and how is it revolutionizing page speed?
Speculative loading is a clever web technology that lets browsers get a head start by preparing content before users actually ask for it.
In a way, it predicts where visitors are likely to go next and quietly loads those pages or resources in the background. This means pages pop up instantly, almost like the site knew what you wanted before you clicked.
Pretty futuristic, right?
This is made possible by the Speculation Rules API, the next step beyond older methods like rel=preload.
Unlike preload, which only hints to download certain resources early (like images or stylesheets), speculation rules give developers detailed instructions to either prefetch critical resources or prerender entire pages before a user even navigates there.
Prefetching loads essential files like HTML, CSS, and key images quietly in the background. Prerendering takes it further – it fully loads and processes the whole page, so when visitors arrive, it’s ready to go immediately.
For WordPress sites with lots of content and predictable navigation paths (think blogs, eCommerce stores, or media sites), this tech fits perfectly.
Speculative loading also directly improves important Core Web Vitals (Google’s key performance metrics), especially Largest Contentful Paint (LCP), which measures how quickly main content loads, and Interaction to Next Paint (INP), which tracks responsiveness to user actions.
Faster LCP and INP mean happier visitors and better search rankings.
Understanding speculation rules
Speculation rules are basically a set of instructions (usually written in JSON) that tell browsers which pages to get ready in advance, and under what conditions. This lets the browser prepare content before a visitor even clicks, speeding up navigation and making your site feel lightning-fast.
To understand speculation rules, it helps to know the difference between a few related techniques:
- Traditional preloading means the browser downloads certain resources early (like images or stylesheets), but it doesn’t process or apply them yet. It’s fast but doesn’t fully prep the page.
- Prefetching builds on this by downloading the HTML and key resources for a page in the background. The browser doesn’t fully render the page yet, but it’s a balanced approach that saves time when the user eventually clicks.
- Prerendering is the most thorough. The browser fully downloads, processes, and renders the entire page behind the scenes. When the user clicks, the page appears instantly, but this uses more bandwidth and system resources.
Speculation rules allow developers to choose how aggressively the browser should preload pages. This is controlled by eagerness levels:
- Conservative only preloads when there’s a strong signal that the user will visit the page. Saves resources but offers moderate speed gains.
- Moderate balances resource use and performance, making it a good default for most sites.
- Eager preloads aggressively, using more bandwidth and CPU but delivering the fastest possible experience.
You can also fine-tune speculation rules based on conditions like user behavior (hovering over a link or tapping), URL patterns (which pages to include or exclude), and even whether the page is currently visible in the viewport.
Right now, speculation rules work everywhere except Safari, so it works well with Chromium-based browsers like Chrome and Edge, as well as Firefox and most Android browsers. Visitors on other browsers will still see your site normally, just without the speed boost.
What makes speculation rules especially useful for WordPress is the ability to tailor preloading based on predictable navigation paths, like from blog lists to posts, or category pages to product pages, giving you fine control that older methods never allowed.
Prefetch vs. prerender: Choosing the right approach for WordPress
Speculative loading’s Speculation Rules API offers a smarter, more flexible way to speed up page loads compared to older methods.
When deciding between prefetching and prerendering for WordPress sites, it’s important to weigh your site’s needs and resources carefully.
Prefetching quietly downloads resources like HTML, CSS, and images in the background without fully rendering the page. It’s a balanced choice that improves perceived speed while keeping resource use moderate.
Prerendering goes all in. It fully loads and processes entire pages behind the scenes, so when users click, the page appears instantly. But this approach uses more bandwidth and CPU, which can impact server resources and mobile visitors’ data plans.
Bear in mind that the quality of your hosting setup is going to make a significant impact on the best strategy here:
For robust hosting environments (like BigScoots’ managed hosting with direct Cloudflare connections), prerendering becomes highly effective because the infrastructure can handle the increased server load and serve cached pages quickly to users. This is especially beneficial for high-traffic sites that need to optimize load times and improve SEO.
For limited hosting environments, prefetching is the safer choice. It enhances user experience by preparing assets in the background without overloading the server or causing slowdowns during traffic spikes.
Your choice also depends on several site-specific factors:
- Theme complexity: Heavy WordPress themes with lots of assets might struggle with prerendering’s resource demands, making prefetching a safer bet. Lightweight themes can usually handle prerendering smoothly.
- Dynamic content: WooCommerce stores, membership sites, or pages with personalized content should be careful with prerendering on predictable flows like checkout, but should use prefetching elsewhere.
- User journey predictability: Sites with clear, linear paths – multi-step forms, sequential content, checkout funnels – can get big wins from prerendering. WordPress sites with more varied navigation do better, sticking mostly to prefetching.
One advanced technique uses WordPress’s internal link structure to build a Dependency Graph, helping decide exactly which pages to prefetch based on actual navigation paths. This means smarter preloading that saves bandwidth and targets what users really need.
Remember: prerendering adds roughly 1.4MB of extra data per prerendered page, which matters especially for mobile users or limited connections.
| TL;DR: Rerendering offers the fastest, smoothest experience on predictable flows and well-optimized sites, while prefetching is a more resource-friendly, flexible choice for less predictable or heavier WordPress setups. |
Understanding the Speculation Rules API for WordPress Sites
With WordPress 6.8, the Speculation Rules API is now natively supported, offering a huge leap forward in web performance by enabling faster page transitions without needing additional plugins.
This feature is set to automatically activate prefetch mode by default, meaning the browser will start loading page resources in the background as users hover over links.
With a conservative eagerness setting, it ensures that prefetching only happens for links users are most likely to click, offering a balanced speed boost without draining resources.
Some pages, like admin pages or those where users are logged in, are excluded from speculative loading to preserve server resources and ensure privacy.
These exclusions help maintain efficiency while maximizing speed for front-end users.
The Speculation Rules API can be implemented in three ways:
- Directly in HTML: Embed a <script type = “speculationrules”> element within the HTML to define static or dynamic rules based on CSS classes or user interactions.
- Using JavaScript: Inject rules dynamically using JavaScript, giving developers the flexibility to apply them based on real-time conditions like user behavior.
- Using an HTTP Header: Deliver rules via the Speculation-Rules HTTP header, which is great for deploying via CDNs without altering the document content, although it limits dynamic modifications from JavaScript.
WordPress also offers the official Speculative Loading plugin developed by the Core Performance team, which enhances the default integration by providing an easy-to-use interface for configuring speculation rules, even for users with no coding knowledge.
The plugin allows custom rule creation, URL pattern exclusions, and more, all designed to make speculation rules accessible to everyone.
For sites looking to maximize the benefits of speculative loading, a progressive implementation strategy is recommended. Start by identifying the most common user journeys using analytics data, then apply speculation rules to those critical paths first. This means you can measure the impact and optimize before rolling out site-wide, a valuable approach for resource-conscious WordPress sites.
How BigScoots amplifies speculative loading benefits through our caching infrastructure
While most WordPress hosts have adopted support for speculative loading since WordPress 6.8, BigScoots has been thinking ahead, offering a deeper, more powerful implementation through our proprietary BigScoots Cache plugin.
From day one, this plugin has integrated Speculation Rules support, delivering significant improvements in Core Web Vitals and real-world user experience for our customers.
Unlike the default WordPress Core, which uses prefetching by default, BigScoots goes for prerendering. This choice is possible because of our robust hosting infrastructure – high resource allocation, fast processing capabilities, and ample bandwidth combined with direct Cloudflare connections.
Our infrastructure can handle the resource-intensive nature of prerendering, where full webpage versions are generated and stored on the server. When users visit, they receive the pre-built page immediately, with zero Time to First Byte (TTFB) delay and no extra rendering wait. This approach fully loads, renders, and executes all JavaScript for target pages in a hidden browser tab. When the user clicks, the page appears instantly with all assets – CSS, fonts, images, and scripts – ready and fully interactive right away, even for complex or dynamic content.
Prerendering is great for high-value navigation flows, like likely next pages, checkout steps, or content-heavy sites, delivering the smoothest, fastest experience that reduces bounce rates and boosts engagement. Plus, it simplifies setup for developers by automatically discovering and loading all required assets, reducing manual configuration headaches.
We also added a fallback in BigScoots Cache that goes beyond what WordPress Core provides: if a browser doesn’t support Speculation Rules, a lightweight JavaScript script switches to classic prefetching using the old <link rel=”prefetch”> method.
This means all visitors benefit from improved loading speed (even logged-in users) since prerendering works silently behind the scenes regardless of CDN involvement.
Take your WordPress performance to the next level with BigScoots
Speculation rules can unlock serious speed improvements, but their real impact depends on the hosting setup behind them. That’s why picking the right WordPress host is more important than ever.
BigScoots includes Cloudflare CDN integration with every plan, laying the groundwork for speculation rules to deliver near-instant page loads. Our edge-first caching architecture ensures preloaded content is served from the closest possible location, cutting latency and boosting responsiveness.
Our infrastructure is built to handle advanced caching strategies that maximize the benefits of the Speculation Rules API, especially for dynamic WordPress sites with complex content.
Plus, our hands-on management and monitoring services help fine-tune speculation rules so your site stays fast and stable under any conditions.
Making the switch to BigScoots is simple and stress-free. Our expert engineering team handles unlimited migrations at no extra cost, ensuring your site moves smoothly to a hosting environment built for the latest performance techniques, so you can focus on growth without the fuss.
Explore BigScoots’ Managed Hosting for WordPress plans and discover how the right infrastructure can turn faster page loads from a nice-to-have into your site’s new standard.
