WordPress在源代码页脚显示资源消耗

function performance( $visible = false ) {
    $stat = sprintf(  '%d queries in %.3f seconds, using %.2fMB memory',
                get_num_queries(),
                timer_stop( 0, 3 ),
                memory_get_peak_usage() / 1024 / 1024
                );
    echo $visible ? $stat : "<!-- {$stat} -->" ;
}
add_action( 'wp_footer', 'performance', 20 );