Django クエリを最適化したい

Djangoで注文のサマリをリスト化して表示したいが、SQLのクエリが多いため、表示するための時間がかかる。
クエリを最適化する方法を知りたい。

class Company(models.Model):
    name = models.CharField(max_length=150)

    def get_order_count(self):
        orders = 0
        for order in self.orders.all():
            orders += 1
        return orders
        
    def get_order_sum(self):
        total_sum = 0
        for contact in self.contacts.all():
            for order in contact.orders.all():
                total_sum += order.total
        return total_sum

class Contact(models.Model):
    company = models.ForeignKey(
        Company, related_name="contacts", on_delete=models.PROTECT)
    first_name = models.CharField(max_length=150)
    last_name = models.CharField(max_length=150, blank=True)

    def get_order_count(self):
        orders = 0
        for order in self.orders.all():
            orders += 1
        return orders

class Order(models.Model):
    order_number = models.CharField(max_length=150)
    company = models.ForeignKey(Company, related_name="orders")
    contact = models.ForeignKey(Contact, related_name="orders")
    total = models.DecimalField(max_digits=18, decimal_places=9)
    order_date = models.DateTimeField(null=True, blank=True)

    def __str__(self):
        return "%s" % self.order_number

class IndexView(ListView):
    template_name = "index.html"
    model = Company
    paginate_by = 50

<body>
	<div style="width:1020px; margin: 0 auto; border:1px solid blue;">
	<table width="1020">
	{% if is_paginated %}
	<tr><td>
		{% if page_obj.has_previous %}
		<a href="?page={{ page_obj.previous_page_number }}" class="pager-prev{% if not page_obj.has_previous %} inactive{% endif %}">&laquo;</a>
		{% endif %}
		</td>
		<td></td>
		<td></td>
		<td>
		{% if page_obj.has_next %}
			<a href="?page={{ page_obj.next_page_number }}" class="pager-next{% if not page_obj.has_next %} inactive{% endif %}">&raquo;</a>
		{% endif %}
		</td>
	</tr>
	{% endif %}
	<tr>
		<th>Name</th>
		<th>Order Count</th>
		<th>Order Sum</th>
		<th>Select</th>
	</tr>
		{% for company in company_list %}
		<tr>
			<td>{{ company.name }}</td>
			<td>{{ company.get_order_count }}</td>
			<td>{{ company.get_order_sum|floatformat:2 }}</td>
			<td><input type="checkbox" name="select{{company.pk}}" id=""></td>
		</tr>
			{% for contact in company.contacts.all %}
			<tr>
				<td>&nbsp;</td>
				<td>{{ contact.first_name }} {{ contact.last_name }}</td>
				<td>Orders: {{ contact.get_order_count }}</td>
				<td></td>
			</tr>
			{% endfor %}
		{% endfor %}
	</table>
	</div>
</body>

期待する表示
|Name|Order Count|Order Sum|Select|
|:--|:--:|--:|
|CompanyA|8|2000|□
||PersonB|Orders: 2|
||PersonC|Orders: 5|
||PersonD|Orders: 1|
|CompanyB|9|1500|□
||PersonD|Orders: 3|
||PersonE|Orders: 1|
||PersonF|Orders: 5|
|CompanyC|15|3500|□
||PersonG|Orders: 10|
||PersonH|Orders: 2|
||PersonI|Orders: 3|