diff --git a/biscuit/apps/chronos/views.py b/biscuit/apps/chronos/views.py
index b769ae438315b1463b6349a0ab48eb53382bb27b..280b0bee98d693a52434b4fbe4bb2661421e08a8 100644
--- a/biscuit/apps/chronos/views.py
+++ b/biscuit/apps/chronos/views.py
@@ -23,7 +23,7 @@ from .tables import LessonsTable
 def timetable(request: HttpRequest) -> HttpResponse:
     context = {}
 
-    lesson_periods = LessonPeriod.objects.all()
+    lesson_periods = LessonPeriod.objects.select_related('substitutions')
 
     if request.GET.get('group', None) or request.GET.get('teacher', None) or request.GET.get('room', None):
         # Incrementally filter lesson periods by GET parameters