Speed of wordpress for admin only

add_action( 'wp_footer', 'tcb_note_server_side_page_speed' );
function tcb_note_server_side_page_speed() {
date_default_timezone_set( get_option( 'timezone_string' ) );
$content = '[ ' . date( 'Y-m-d H:i:s T' ) . ' ] ';
$content .= 'Page created in ';
$content .= timer_stop( $display = 0, $precision = 2 );
$content .= ' seconds from ';
$content .= get_num_queries();
$content .= ' queries';
if( ! current_user_can( 'administrator' ) ) $content = "";
echo $content;
}