Schedule Cron to Delete Expired Transients

Over time, expired transients pile up in the wp_options table and slow down queries. This snippet schedules a weekly cleanup. For more on improving WordPress performance.

if ( ! wp_next_scheduled( 'savvy_cleanup_transients' ) ) {
    wp_schedule_event( time(), 'weekly', 'savvy_cleanup_transients' );
}

add_action( 'savvy_cleanup_transients', function () {
    global $wpdb;
    $wpdb->query(
        "DELETE a, b FROM {$wpdb->options} a
        LEFT JOIN {$wpdb->options} b
            ON b.option_name = REPLACE( a.option_name, '_transient_timeout_', '_transient_' )
        WHERE a.option_name LIKE '\_transient\_timeout\_%'
            AND a.option_value < UNIX_TIMESTAMP()"
    );
} );

Add to functions.php. The cron runs once a week and removes only expired transients.