diff --git a/app/(tabs)/calendar/hooks/useCalendarState.ts b/app/(tabs)/calendar/hooks/useCalendarState.ts
index 4cfd4e333..8c88a91aa 100644
--- a/app/(tabs)/calendar/hooks/useCalendarState.ts
+++ b/app/(tabs)/calendar/hooks/useCalendarState.ts
@@ -1,5 +1,5 @@
-import { useState, useRef, useEffect, useCallback } from 'react';
-import { Dimensions, FlatList } from 'react-native';
+import { useState, useRef, useEffect, useCallback } from "react";
+import { Dimensions, FlatList } from "react-native";
 import { getWeekNumberFromDate } from "@/database/useHomework";
 import { warn } from "@/utils/logger/logger";
 
@@ -28,17 +28,17 @@ export function useCalendarState() {
     base.setHours(0, 0, 0, 0);
     const target = new Date(d);
     target.setHours(0, 0, 0, 0);
-    const diff = Math.round((target.getTime() - base.getTime()) / (1000 * 60 * 60 * 24));
+    const diff = Math.round(
+      (target.getTime() - base.getTime()) / (1000 * 60 * 60 * 24)
+    );
     return INITIAL_INDEX + diff;
   }, []);
 
   const handleDateChange = useCallback((newDate: Date) => {
     setDate(newDate);
     const newWeekNumber = getWeekNumberFromDate(newDate);
-    if (newWeekNumber !== weekNumber) {
-      setWeekNumber(newWeekNumber);
-    }
-  }, [weekNumber]);
+    setWeekNumber(prev => (prev !== newWeekNumber ? newWeekNumber : prev));
+  }, []);
 
   // Sync FlatList with date
   useEffect(() => {
@@ -58,7 +58,7 @@ export function useCalendarState() {
             animated: false,
           });
         } catch (e) {
-          warn(String(e))
+          warn(String(e));
         }
       }
     }
@@ -68,31 +68,41 @@ export function useCalendarState() {
     }
   }, [date, getIndexFromDate, currentIndex, weekNumber]);
 
-  const onMomentumScrollEnd = useCallback((e: any) => {
-    const newIndex = Math.round(e.nativeEvent.contentOffset.x / windowWidth);
-    if (newIndex !== currentIndex) {
-      setCurrentIndex(newIndex);
-      const newDate = getDateFromIndex(newIndex);
-      setDate((prev) => prev.getTime() !== newDate.getTime() ? newDate : prev);
-    }
-  }, [windowWidth, currentIndex, getDateFromIndex]);
+  const onMomentumScrollEnd = useCallback(
+    (e: any) => {
+      const newIndex = Math.round(e.nativeEvent.contentOffset.x / windowWidth);
+      if (newIndex !== currentIndex) {
+        setCurrentIndex(newIndex);
+        const newDate = getDateFromIndex(newIndex);
+        setDate(prev =>
+          prev.getTime() !== newDate.getTime() ? newDate : prev
+        );
+      }
+    },
+    [windowWidth, currentIndex, getDateFromIndex]
+  );
 
   const lastEmittedIndex = useRef(currentIndex);
 
-  const onScroll = useCallback((e: any) => {
-    const offsetX = e.nativeEvent.contentOffset.x;
-    const newIndex = Math.round(offsetX / windowWidth);
-    if (newIndex !== lastEmittedIndex.current) {
-      lastEmittedIndex.current = newIndex;
-      setCurrentIndex(newIndex);
-      const newDate = getDateFromIndex(newIndex);
-      setDate((prev) => prev.getTime() !== newDate.getTime() ? newDate : prev);
-      const newWeekNumber = getWeekNumberFromDate(newDate);
-      if (newWeekNumber !== weekNumber) {
-        setWeekNumber(newWeekNumber);
+  const onScroll = useCallback(
+    (e: any) => {
+      const offsetX = e.nativeEvent.contentOffset.x;
+      const newIndex = Math.round(offsetX / windowWidth);
+      if (newIndex !== lastEmittedIndex.current) {
+        lastEmittedIndex.current = newIndex;
+        setCurrentIndex(newIndex);
+        const newDate = getDateFromIndex(newIndex);
+        setDate(prev =>
+          prev.getTime() !== newDate.getTime() ? newDate : prev
+        );
+        const newWeekNumber = getWeekNumberFromDate(newDate);
+        if (newWeekNumber !== weekNumber) {
+          setWeekNumber(newWeekNumber);
+        }
       }
-    }
-  }, [windowWidth, getDateFromIndex, weekNumber]);
+    },
+    [windowWidth, getDateFromIndex, weekNumber]
+  );
 
   return {
     date,
@@ -107,6 +117,6 @@ export function useCalendarState() {
     onMomentumScrollEnd,
     onScroll,
     INITIAL_INDEX,
-    windowWidth
+    windowWidth,
   };
 }
diff --git a/app/(tabs)/calendar/index.tsx b/app/(tabs)/calendar/index.tsx
index f06512be8..3328a11ed 100644
--- a/app/(tabs)/calendar/index.tsx
+++ b/app/(tabs)/calendar/index.tsx
@@ -1,4 +1,4 @@
-import React, { useRef, useCallback, useState } from "react";
+import React, { useRef, useCallback, useState, useMemo } from "react";
 import { View, FlatList, StyleSheet } from "react-native";
 import { useTheme } from "@react-navigation/native";
 import { useCalendarState } from "./hooks/useCalendarState";
@@ -20,7 +20,6 @@ export default function TabOneScreen() {
   const {
     date,
     weekNumber,
-    currentIndex,
     flatListRef,
     getDateFromIndex,
     handleDateChange,
@@ -37,15 +36,26 @@ export default function TabOneScreen() {
     isLoading
   } = useTimetableData(weekNumber, date);
 
+  const timetableMap = useMemo(() => {
+    const map = new Map<number, (typeof timetable)[number]["courses"]>();
+
+    timetable.forEach(day => {
+      const normalized = new Date(day.date);
+      normalized.setHours(0, 0, 0, 0);
+      const key = normalized.getTime();
+      map.set(key, day.courses);
+    });
+
+    return map;
+  }, [timetable]);
+
   const renderDay = useCallback(({ index }: { index: number }) => {
     const dayDate = getDateFromIndex(index);
     const normalizedDate = new Date(dayDate);
+
     normalizedDate.setHours(0, 0, 0, 0);
-    const dayCourses = timetable.find(d => {
-      const dDate = new Date(d.date);
-      dDate.setHours(0, 0, 0, 0);
-      return dDate.getTime() === normalizedDate.getTime();
-    })?.courses || [];
+
+    const dayCourses = timetableMap.get(normalizedDate.getTime()) || [];
 
     return (
       <CalendarDay
@@ -59,7 +69,14 @@ export default function TabOneScreen() {
         tabBarHeight={tabBarHeight}
       />
     );
-  }, [getDateFromIndex, timetable, manualRefreshing, handleRefresh, colors, headerHeight]);
+  }, [getDateFromIndex, timetableMap, manualRefreshing, handleRefresh, colors, headerHeight, insets, tabBarHeight]);
+
+  const extraData = useMemo(() => ({
+    manualRefreshing,
+    headerHeight,
+    colors,
+    timetableVersion: timetable.length
+  }), [manualRefreshing, headerHeight, colors, timetable.length]);
 
   return (
     <>
@@ -83,18 +100,23 @@ export default function TabOneScreen() {
           renderItem={renderDay}
           keyExtractor={(_, index) => "renderDay:" + String(index)}
           onScroll={onScroll}
-          decelerationRate={0.98}
-          disableIntervalMomentum={true}
+
+          decelerationRate="fast"
+          disableIntervalMomentum={false}
           scrollEventThrottle={16}
           onMomentumScrollEnd={onMomentumScrollEnd}
           snapToInterval={windowWidth}
+          snapToAlignment="start"
           bounces={false}
-          windowSize={4}
-          maxToRenderPerBatch={3}
-          initialNumToRender={3}
+
+          windowSize={5}
+          maxToRenderPerBatch={2}
+          initialNumToRender={1}
+          updateCellsBatchingPeriod={50}
+
           showsVerticalScrollIndicator={false}
           removeClippedSubviews
-          extraData={{ manualRefreshing, headerHeight, colors, timetable }}
+          extraData={extraData}
         />
       </View>
     </>