Connection Optimization - BoostPro Docs

Auto-preconnect external domains, preload assets with advanced rules, and auto-detect the LCP image.

Overview

Every external resource your site loads requires the browser to establish a connection: DNS lookup, TCP handshake, and TLS negotiation. These steps add latency before any data transfers. BoostPro's connection optimization features let you pre-establish connections and preload critical assets so they're ready when needed.

These settings are located on the BoostPro → Optimization tab, under the Connections section.

Auto-preconnect

BoostPro automatically detects external domains referenced by your enqueued scripts and stylesheets, then adds preconnect hints via the wp_resource_hints filter. This tells the browser to begin DNS + TCP + TLS setup for those domains early, saving connection time when the actual resources are requested.

Custom preconnect domains

For domains that aren't automatically detected (API endpoints, third-party services, analytics providers), you can add custom preconnect domains manually. Enter one domain per line. Domains are automatically prefixed with https:// if no protocol is specified.

cdn.example.com
api.analytics.com
maps.googleapis.com

Tip

Limit preconnect to 4-6 domains. Too many preconnects can saturate the browser's connection pool and actually slow things down.

Preload assets

Preloading tells the browser to fetch specific resources with high priority before it would normally discover them. Enter one URL per line. BoostPro auto-detects the resource type from the file extension.

To override the auto-detected type, use the as:type syntax:

/wp-content/themes/mytheme/fonts/custom.woff2 as:font
/wp-content/themes/mytheme/hero.webp as:image
/wp-content/plugins/myplugin/critical.css as:style

Supported types: font, style, script, image, document.

Advanced preload rules

For more granular control, advanced preload rules let you define conditions for when and where assets are preloaded:

Device targeting: all devices, mobile only, or desktop only
Page conditions: specific URLs, post types, or URL patterns
Fetch priority: auto, high, or low

This is useful when different pages have different critical resources. For example, you might preload a hero image only on the homepage, or a specific font only on landing pages.

Auto-preload LCP image

The Largest Contentful Paint (LCP) element is often a hero image or large above-the-fold graphic. The faster this image loads, the better your LCP score.

When enabled, BoostPro auto-detects the first large CSS background image or <img> element and adds a preload hint in the <head>:

<link rel="preload" as="image" href="/wp-content/uploads/hero.webp">

This gives the browser a head start on downloading the LCP image before it would normally discover it through HTML parsing and CSS evaluation.

Important

Preloading assets the browser doesn't actually use wastes bandwidth. Only preload resources that appear on every page or that are critical to above-the-fold rendering.