diff --git a/components/schedule/ScheduleContainer.tsx b/components/schedule/ScheduleContainer.tsx
index 33d877a4..93a40372 100644
--- a/components/schedule/ScheduleContainer.tsx
+++ b/components/schedule/ScheduleContainer.tsx
@@ -20,7 +20,8 @@ export default function ScheduleContainer({ initialSchedule, year }: Readonly<Sc
       return initialSchedule;
     }
 
-    const filterSessions = (sessions: GridSession[]) => sessions.filter((s) => savedSessionIds.includes(s.id) || s.isServiceSession);
+    const savedIdsSet = new Set(savedSessionIds);
+    const filterSessions = (sessions: GridSession[]) => sessions.filter((s) => savedIdsSet.has(s.id) || s.isServiceSession);
 
     return initialSchedule.map((day) => ({
       ...day,