Invalidate cache on new order
In your code you are only caching until the dateOrdered of the latest order. That means that viewing the page will always be ahead of the cache time.

You could look to do the following:

{% set latestOrder = craft.commerce.orders.order('dateOrdered DESC').first() %}
{% set cacheKey = 'orders-' ~ latestOrder.dateOrdered|date('U') %}

{% cache using key cacheKey %}
  {% set orders = craft.commerce.orders.order('dateOrdered DESC').find() %}
  &lt;ul&gt;
    {% for order in orders %}
      &lt;li&gt;{{ order.id }}&lt;/li&gt;
    {% endfor %}
  &lt;/ul&gt;
{% endcache %}


This creates a cache key based on the date of the latest order. Therefore, when there is a new order this key will change.