Don't include migrate.js in production, if you know you won't need it.

expat.php

/**
 * Expat
 * Don't include migrate.js in production, if you know you won't need it.
 * @param  string &$scripts enqueued scripts
 * @version 0.1.0
 * @link https://gist.github.com/shinmai/7d5fdbb855850c526af5ae2b36613492
 * @license http://www.wtfpl.net/txt/copying/ WTFPL
 * @author Aapo Saaristo <aapo.saaristo@gmail.com>
 */
function expat( &$scripts){
	if(is_admin()) return;
	$scripts->remove( 'jquery');
	$scripts->add( 'jquery', false, array( 'jquery-core' ), '1.10.2' );
}
//add_filter( 'wp_default_scripts', 'expat' ); // Uncomment to enable