get weight sum along with bills to scale

otherwise, we need to get the weight sum for each displayed bill.
Here, we are much more scalable

ihatemoney/models.py

@@ -246,13 +246,29 @@ class Project(db.Model):
 
     def get_bills(self):
         """Return the list of bills related to this project"""
+        return self.ordered_bills(self.get_bills_unordered())
+
+    def ordered_bills(self, query):
         return (
-            self.get_bills_unordered()
+            query.order_by(Bill.date.desc())
-            .order_by(Bill.date.desc())
             .order_by(Bill.creation_date.desc())
             .order_by(Bill.id.desc())
         )
 
+    def get_bill_weights(self):
+        return (
+            db.session.query(func.sum(Person.weight), Bill)
+            .options(orm.subqueryload(Bill.owers))
+            .select_from(Person)
+            .join(billowers, Bill, Project)
+            .filter(Person.project_id == Project.id)
+            .filter(Project.id == self.id)
+            .group_by(Bill.id)
+        )
+
+    def get_bill_weights_ordered(self):
+        return self.ordered_bills(self.get_bill_weights())
+
     def get_member_bills(self, member_id):
         """Return the list of bills related to a specific member"""
         return (

ihatemoney/templates/list_bills.html

@@ -1,7 +1,7 @@
 {% extends "sidebar_table_layout.html" %}
 
-{%- macro bill_amount(bill, currency=bill.original_currency, amount=bill.amount) %}
+{%- macro bill_amount_weighted(bill, weights, currency=bill.original_currency, amount=bill.amount) %}
-    {{ amount|currency(currency) }} ({{ _("%(amount)s each", amount=bill.pay_each_default(amount)|currency(currency)) }})
+    {{ amount|currency(currency) }} ({{ _("%(amount)s each", amount=(amount / weights)|currency(currency)) }})
 {% endmacro -%}
 
 {% block title %} - {{ g.project.name }}{% endblock %}
@@ -109,7 +109,7 @@
                 </th><th>{{ _("Actions") }}</th></tr>
             </thead>
         <tbody>
-        {% for bill in bills.items %}
+        {% for (weights, bill) in bills.items %}
         <tr owers="{{bill.owers|join(',','id')}}" payer="{{bill.payer.id}}">
                 <td>
                     <span data-toggle="tooltip" data-placement="top"
@@ -128,8 +128,8 @@
                 {%- endif %}</td>
                 <td>
                     <span data-toggle="tooltip" data-placement="top"
-                        title="{{ bill_amount(bill, g.project.default_currency, bill.converted_amount) if bill.original_currency != g.project.default_currency else '' }}">
+                        title="{{ bill_amount_weighted(bill, weights, g.project.default_currency, bill.converted_amount) if bill.original_currency != g.project.default_currency else '' }}">
-                        {{ bill_amount(bill) }}
+                        {{ bill_amount_weighted(bill, weights) }}
                     </span>
                 </td>
                 <td class="bill-actions">

ihatemoney/web.py

@@ -654,11 +654,8 @@ def list_bills():
     # set the last selected payer as default choice if exists
     if "last_selected_payer" in session:
         bill_form.payer.data = session["last_selected_payer"]
-    # Preload the "owers" relationship for all bills
+    bills = g.project.get_bill_weights_ordered().paginate(
-    bills = (
+        per_page=500, error_out=True
-        g.project.get_bills()
-        .options(orm.subqueryload(Bill.owers))
-        .paginate(per_page=100, error_out=True)
     )
 
     return render_template(