icingaweb2/modules/monitoring/application/views/scripts/show/components/perfdata.phtml

<?php if ($this->object->perfdata): ?>
    <div class="panel panel-default">
        <div class="panel-heading">
            <span>Perfdata</span>
        </div>
        <div class="panel-body">
            <?= $this->perfdata($this->object->perfdata); ?>
        </div>
    </div>
<?php endif; ?>