重新加载页面使服务器负担沉重

Question

我在管理面板中做了一个计数器，以获取（新订单，新评论）的数量，并按间隔时间进行调用，但这似乎会使服务器频繁崩溃，因此如果有更好的主意来实现它。

   <a >
        <i class="fa fa-truck"></i>
        <span>Orders</span><span class="label label-danger pull-right mail-info" id="ordernumber"></span>
    </a>
    <ul class="sub">
        <li><a href="new-orders.php"><span>New orders</span> <span class="label label-theme  mail-info" id="ordernumber1"></span></a>            
        </li>
        <li><a href="confirmed-orders.php">Comfirmed orders</a></li>
        <li><a href="finished-orders.php">finished orders</a></li>
    </ul>
    </li>
<script>
setInterval(function(){
    $('#ordernumber').load("include/ordercount.php").fadeIn("slow");
    $('#ordernumber1').load("include/ordercount.php").fadeIn("slow");
},1500);
</script>

这是ordercount.php

<?php 

require_once('databaseCon.php');
$stmt=$conn->prepare("SELECT * From orders WHERE order_state=?");
$stmt->execute(array('pending'));
$count=$stmt->rowCount();
if($count>0)
    echo $count;
?>