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Speculative Loading

By WordPress Performance Team

Performance & Optimization / Caching Solutions

Reviewed by Omar Dabbas

Trusted WordPress expert with 20+ years of experience evaluating plugins for the WP ecosystem.

Speculative Loading Review - In-Depth Analysis

This plugin enhances page loading speeds by enabling browsers to speculatively prerender or prefetch pages based on user interactions. It utilizes the Speculation Rules API for improved performance.

Performance Overview

WPS Score

6.46/10

User Rating

5/5 (based on 18+ reviews)

Active Installations

70,000+

Update Frequency

Below Average It is calculated using the weighted average of same category plugins.

Security Score

1 / 10 (Very Low Risk) It is calculated using the weighted average of all versions.

What It Does

This plugin adds support for the Speculation Rules API, which allows defining rules by which certain URLs are dynamically prefetched or prerendered. This core Speculative Loading functionality was merged into WordPress 6.8, but it only prefetches with conservative eagerness by default. In contrast, this plugin defaults to prerendering with moderate eagerness when interacting with a link, and it provides a user interface to customize the mode and eagerness via the Speculative Loading section on the Settings > Reading admin screen.

By default, speculative loading is only enabled for logged-out users, since unauthenticated pages are typically only eligible for caching and so more efficient to prefetch/prerender. This means that sites with frequent logged-in users on the frontend—such as e-commerce, forums, or membership sites—will not benefit from the feature. If your server can handle the additional load, you can opt in to enable speculative loading for all logged-in users or for administrators only. This setting exclusively affects frontend pages; admin screens are always excluded.

A filter can be used to exclude certain URL paths from being eligible for prefetching and prerendering. Alternatively, you can add the no-prerender CSS class to any link that should not be prerendered. See FAQ for more information.

The Speculation Rules API is a new web API, and the functionality used by the plugin is supported in Chromium-based browsers such as Chrome, Edge, or Opera using version 121 or above. Other browsers such as Safari and Firefox will ignore the functionality with no ill effects; they will simply not benefit from the speculative loading.

Comparing to Alternatives

Speculative Loading stands alone in its category with no close direct alternatives available, making it a unique choice for users seeking this functionality.

Top alternatives

Strengths

Significantly improves perceived page load speed for users.
Highly functional and reliable across various WordPress and WooCommerce sites.
Consistently praised for its impressive performance and speed.
Easy to use and integrates well without issues.
Demonstrates noticeable speed improvements even on heavy sites.

Weaknesses

No direct alternatives to compare feature sets or pricing.
Lacks a pro version with advanced features or support options.

User Sentiment Analysis

With a perfect 5-star rating from all 18 reviewers, user feedback is overwhelmingly positive, highlighting the plugin's effectiveness and reliability.

Positive highlights

'Very fast and functional – Thanks for this.' – mrimpact
'Ein absolut sinnvolles Plugin' (A truly meaningful plugin) – lacoste89
'Amazing results on install. Will continue to check this one out.' – Hudson Atwell
'Seriously Impressive' and faster than similar plugins – groggy72
'Does what it needs to do.' – OllieJones

Common complaints

Weaknesses

No reported weaknesses or issues from users.
No security vulnerabilities detected, indicating a secure plugin.

Who Should Use This?

Best for

Users looking for a reliable and effective plugin to improve perceived page load speed without the need for advanced features or paid upgrades.

Not ideal for

Those seeking a plugin with a pro version offering additional premium features or dedicated support may find this plugin limited.

Pricing & Value

Free version includes

The free version offers full functionality with impressive speed improvements and no limitations.

Final Verdict

Speculative Loading is a standout plugin delivering excellent performance and user satisfaction with a perfect rating and no reported issues or vulnerabilities. Its unique position without direct alternatives highlights its specialized value.

While it lacks a pro version and advanced features, its free offering is robust and effective, making it an excellent choice for users prioritizing speed improvements without additional costs or complexity.

Other Notable Features

Here are a few other notable features of this free Speculative Loading plugin.

Javascript

Performance

Prefetch

Prerender

Speculation Rules

FAQ

Not every URL can be reasonably prerendered. Prerendering static content is typically reliable, however prerendering interactive content, such as a logout URL, can lead to issues. For this reason, certain WordPress core URLs such as /wp-login.php and /wp-admin/* are excluded from prefetching and prerendering. Additionally, any URLs generated with wp_nonce_url() (or which contains the _wpnonce query var) and nofollow links are also ignored. You can exclude additional URL patterns by using the plsr_speculation_rules_href_exclude_paths filter.

The following example ensures that URLs like https://example.com/cart/ or https://example.com/cart/foo are excluded from prefetching and prerendering:

<?php add_filter(     'plsr_speculation_rules_href_exclude_paths',     function ( array $exclude_paths ): array {         $exclude_paths[] = '/cart/*';         return $exclude_paths;     } );

Keep in mind that sometimes it may be useful to exclude a URL from prerendering while still allowing it to be prefetched. For example, a page with client-side JavaScript to update user state should probably not be prerendered, but it would be reasonable to prefetch.

For this purpose, the plsr_speculation_rules_href_exclude_paths filter receives the current mode (either “prefetch” or “prerender”) to provide conditional exclusions.

The following example ensures that URLs like https://example.com/products/... cannot be prerendered, while still allowing them to be prefetched:

<?php add_filter(     'plsr_speculation_rules_href_exclude_paths',     function ( array $exclude_paths, string $mode ): array {         if ( 'prerender' === $mode ) {             $exclude_paths[] = '/products/*';         }         return $exclude_paths;     },     10,     2 );

As mentioned above, adding the no-prerender CSS class to a link will prevent it from being prerendered (but not prefetched). Additionally, links with rel=nofollow will neither be prefetched nor prerendered because some plugins add this to non-idempotent links (e.g. add to cart); such links ideally should rather be buttons which trigger a POST request or at least they should use wp_nonce_url().

For safety reasons, the entire speculative loading feature is disabled by default for logged-in users and for sites that do not use pretty permalinks. The latter is the case because plugins often use URLs with custom query parameters to let users perform actions, and such URLs should not be speculatively loaded. For sites without pretty permalinks, it is impossible or at least extremely complex to differentiate between which query parameters are Core defaults and which query parameters are custom.

If you are running this plugin on a site without pretty permalinks and are confident that there are no custom query parameters in use that can cause state changes, you can opt in to enabling speculative loading via the plsr_enabled_without_pretty_permalinks filter:

<?php add_filter( 'plsr_enabled_without_pretty_permalinks', '__return_true' );

Contributors and developers

“Speculative Loading” is open source software. The following people have contributed to this plugin.

WordPress Performance Team

WordPress.org

Free Version

WPS

6.46

Average

Ratings

5 out of 5 | 18

Version

1.7.0

Last updated

1 month ago

Active installations

70,000+

WordPress version

7.1.3 or higher

PHP version

7.4 or higher

Languages

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Speculative Loading Review - In-Depth Analysis

Performance Overview

What It Does

Comparing to Alternatives

User Sentiment Analysis

Who Should Use This?

Pricing & Value

Final Verdict

Other Notable Features

FAQ

Contributors and developers

Ratings

Reviews (18)

Sort by:

Contributors & Developers

Interested in development?

Changelog

Security Status

Secure

No Unpatched Vulnerabilities

Known Vulnerabilities (0)

Previous Versions

WPS

6.46

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