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Speculative Loading
Prefetch or prerender pages before the user clicks using the browser Speculation Rules API.
Last updated Feb 21, 2026
Overview
Speculative loading uses the browser's Speculation Rules API to load pages before the user clicks a link. When a visitor hovers over or clicks a link, BoostPro instructs the browser to begin loading that page in advance, making navigation feel nearly instant.
This setting is located on the BoostPro → Optimization tab, under the Speculation Rules section.
AdvancedPrefetch vs prerender
BoostPro supports two speculative loading modes:
| Prefetch | Prerender (default) | |
|---|---|---|
| What it does | Downloads the HTML document only | Fully renders the page in a hidden tab |
| Bandwidth usage | Low (HTML only) | Higher (HTML + all subresources) |
| Navigation speed | Faster than normal (still needs rendering) | Near-instant (page is already rendered) |
| Best for | Metered connections, high-traffic sites | Most sites seeking the fastest navigation |
Eagerness levels
Eagerness controls when speculative loading begins:
- Conservative: preloads on mousedown or touchstart. The safest option with approximately 100ms of head start. Only loads pages the user is actively clicking.
- Moderate (default): preloads on hover. Gives approximately 200-400ms of head start, which is enough to make most navigations feel instant.
- Eager: preloads all visible links on the page. The most aggressive option with the highest bandwidth usage, but ensures every link is ready before the user interacts.
Tip
Moderate eagerness with prerender is the sweet spot for most sites. It gives a noticeable speed boost on navigation without excessive bandwidth usage.
Automatic exclusions
BoostPro automatically excludes URLs that should never be speculatively loaded:
/wp-admin/*/wp-login.php- WooCommerce cart, checkout, and account pages
- URLs with query strings
Custom exclusion patterns
You can add your own exclusion patterns, one per line. Any URL containing the pattern will be skipped by speculative loading.
/members/
/private/
/checkout/WordPress 6.8+ compatibility
WordPress 6.8 and later includes its own speculation rules implementation. When BoostPro detects WordPress 6.8+, it automatically skips its own speculation rules output to avoid duplicates. You can use either WordPress's built-in implementation or disable it and use BoostPro's instead.
Skipped contexts
Speculation rules are not output in the following contexts to avoid unnecessary processing:
- Logged-in users
- Admin pages
- AJAX requests
- REST API requests
Browser support
The Speculation Rules API is supported in Chromium 109+ (Chrome, Edge, Opera). Browsers that don't support the API simply ignore the speculation rules with zero negative impact. No JavaScript fallback is needed, and no resources are wasted on unsupported browsers.
Important
Prerender mode loads full pages in hidden tabs. On metered connections or for sites with expensive server-side operations, consider using prefetch mode instead to reduce bandwidth and server load.