improved performance and battery usage on older devices

lib/state/app/modules/foreign_timetable/bloc/foreign_timetable_bloc.dart

@@ -142,12 +142,11 @@ class ForeignTimetableBloc
 
       add(
         Emit(
-          (s) => s.copyWith(
+          (s) => s.withReferenceData(
             rooms: rooms,
             subjects: subjects,
             schoolHolidays: schoolHolidays,
             schoolyear: schoolyear,
-            dataVersion: s.dataVersion + 1,
           ),
         ),
       );
@@ -157,11 +156,7 @@ class ForeignTimetableBloc
 
     try {
       final timegrid = await repo.data.getTimegrid();
-      add(
-        Emit(
-          (s) => s.copyWith(timegrid: timegrid, dataVersion: s.dataVersion + 1),
-        ),
-      );
+      add(Emit((s) => s.withReferenceData(timegrid: timegrid)));
     } catch (_) {
       // Timegrid load failure falls back to a hardcoded schedule in the UI.
     }