diff --git a/biscuit/apps/alsijil/views.py b/biscuit/apps/alsijil/views.py
index 87adc7f1381a55bc8023953bf29555e28498a59b..1f48f84c1d25879daec5fb72bcd5a697c35175c7 100644
--- a/biscuit/apps/alsijil/views.py
+++ b/biscuit/apps/alsijil/views.py
@@ -96,8 +96,11 @@ def group_week(request: HttpRequest, week: Optional[int] = None) -> HttpResponse
     periods_by_day_unsorted = {}
     if group:
         for act_group in [group] + list(group.child_groups.all()):
-            for lesson in act_group.lessons.filter(date_start__lte=week_start, date_end__gte=week_end):
-                for lesson_period in lesson.lesson_periods.select_related('period').all():
+            for lesson in act_group.lessons.select_related(
+                'lesson_period',
+                'lesson_period__period'
+            ).filter(date_start__lte=week_start, date_end__gte=week_end):
+                for lesson_period in lesson.lesson_periods.all():
                     periods_by_day_unsorted.setdefault(
                         lesson_period.period.weekday, []).append(lesson_period)