Preload external PHP information

WordPress has Transient and Object Cache APIs available. In a default WordPress install, Transients are stored in the database while Object Cache is stored in memory for the duration of the request. You can change this configuration to using something like Redis, Memcache, or APC to store and access this faster.

In your case, you’d want to use Transients.

Here’s a good example from the Transient API Codex:

<?php
// Get any existing copy of our transient data
if ( false === ( $special_query_results = get_transient( 'special_query_results' ) ) ) {
    // It wasn't there, so regenerate the data and save the transient
     $special_query_results = new WP_Query( 'cat=5&order=random&tag=tech&post_meta_key=thumbnail' );
     set_transient( 'special_query_results', $special_query_results, 12 * HOUR_IN_SECONDS );
}

// Use the data like you would have normally...
?>