perf: Aggressive optimization for playlist switching to make it snappy - Add React.startTransition to batch state updates in usePaginatedSongs - Optimize playlist selection handler with immediate navigation - Memoize click handlers in PlaylistItem to prevent recreation - Use replace navigation to avoid history stack delays - Should dramatically reduce 600+ms playlist switching delay

packages/frontend/src/App.tsx

@@ -1,6 +1,6 @@
 import { Box, Button, Flex, Heading, Spinner, Text, useBreakpointValue, IconButton, Drawer, DrawerBody, DrawerHeader, DrawerOverlay, DrawerContent, useDisclosure, Modal, ModalOverlay, ModalContent, ModalHeader, ModalBody, ModalFooter, VStack } from "@chakra-ui/react";
 import { ChevronLeftIcon, ChevronRightIcon, SettingsIcon } from "@chakra-ui/icons";
-import { useState, useRef, useEffect, useCallback } from "react";
+import React, { useState, useRef, useEffect, useCallback } from "react";
 import { useNavigate, useLocation, Routes, Route } from "react-router-dom";
 import { PaginatedSongList } from "./components/PaginatedSongList";
 import { PlaylistManager } from "./components/PlaylistManager";
@@ -154,13 +154,15 @@ export default function RekordboxReader() {
   }, [currentPlaylist, playlists, navigate, xmlLoading]);
 
   const handlePlaylistSelect = (name: string) => {
-    setSelectedSong(null); // Clear selected song when changing playlists
+    // Clear selected song immediately to prevent stale state
+    setSelectedSong(null);
+    
+    // Navigate immediately without any delays
     if (name === "All Songs") {
-      navigate("/");
+      navigate("/", { replace: true });
     } else {
-      // Use encodeURIComponent to properly handle spaces and special characters
       const encodedName = encodeURIComponent(name);
-      navigate(`/playlists/${encodedName}`);
+      navigate(`/playlists/${encodedName}`, { replace: true });
     }
   };
 

packages/frontend/src/components/PaginatedSongList.tsx

@@ -50,6 +50,8 @@ const SongItem = memo<{
   onToggleSelection: (songId: string) => void;
   showCheckbox: boolean;
 }>(({ song, isSelected, isHighlighted, onSelect, onToggleSelection, showCheckbox }) => {
+  // Memoize the formatted duration to prevent recalculation
+  const formattedDuration = useMemo(() => formatDuration(song.totalTime || ''), [song.totalTime]);
   const handleClick = useCallback(() => {
     onSelect(song);
   }, [onSelect, song]);
@@ -89,7 +91,7 @@ const SongItem = memo<{
       </Box>
       <Box textAlign="right" ml={2}>
         <Text fontSize="xs" color="gray.500">
-          {formatDuration(song.totalTime || '')}
+          {formattedDuration}
         </Text>
         <Text fontSize="xs" color="gray.600">
           {song.averageBpm} BPM
@@ -213,7 +215,7 @@ export const PaginatedSongList: React.FC<PaginatedSongListProps> = memo(({
         showCheckbox={selectedSongs.size > 0 || depth === 0}
       />
     ));
-  }, [songs, selectedSongs, selectedSongId, handleSongSelect, toggleSelection, depth]);
+  }, [songs, selectedSongs, selectedSongId, toggleSelection, depth]); // Removed handleSongSelect since it's already memoized
 
   // Use total playlist duration if available, otherwise calculate from current songs
   const totalDuration = useMemo(() => {
@@ -257,7 +259,7 @@ export const PaginatedSongList: React.FC<PaginatedSongListProps> = memo(({
             // Reset the flag after a short delay to prevent multiple triggers
             timeoutRef.current = setTimeout(() => {
               isTriggeringRef.current = false;
-            }, 1000);
+            }, 100);
           }
         },
         { 

packages/frontend/src/components/PlaylistManager.tsx

@@ -36,27 +36,50 @@ interface PlaylistManagerProps {
   onPlaylistMove: (playlistName: string, targetFolderName: string | null) => void;
 }
 
-const getButtonStyles = (isSelected: boolean) => ({
+// Memoized button styles to prevent unnecessary re-renders
+const selectedButtonStyles = {
   width: "100%",
   display: "flex",
   alignItems: "center",
   justifyContent: "space-between",
-  bg: isSelected ? "blue.800" : "transparent",
-  color: isSelected ? "white" : "gray.100",
-  fontWeight: isSelected ? "600" : "normal",
+  bg: "blue.800",
+  color: "white",
+  fontWeight: "600",
   borderRadius: "md",
   px: 4,
   py: 2,
   cursor: "pointer",
   transition: "all 0.2s",
   _hover: {
-    bg: isSelected ? "blue.600" : "whiteAlpha.200",
+    bg: "blue.600",
     transform: "translateX(2px)",
   },
   _active: {
-    bg: isSelected ? "blue.700" : "whiteAlpha.300",
+    bg: "blue.700",
   },
-});
+};
+
+const unselectedButtonStyles = {
+  width: "100%",
+  display: "flex",
+  alignItems: "center",
+  justifyContent: "space-between",
+  bg: "transparent",
+  color: "gray.100",
+  fontWeight: "normal",
+  borderRadius: "md",
+  px: 4,
+  py: 2,
+  cursor: "pointer",
+  transition: "all 0.2s",
+  _hover: {
+    bg: "whiteAlpha.200",
+    transform: "translateX(2px)",
+  },
+  _active: {
+    bg: "whiteAlpha.300",
+  },
+};
 
 interface PlaylistItemProps {
   node: PlaylistNode;
@@ -68,7 +91,7 @@ interface PlaylistItemProps {
   allFolders: { name: string }[];
 }
 
-const PlaylistItem: React.FC<PlaylistItemProps> = ({
+const PlaylistItem: React.FC<PlaylistItemProps> = React.memo(({
   node,
   level,
   selectedItem,
@@ -78,6 +101,15 @@ const PlaylistItem: React.FC<PlaylistItemProps> = ({
   allFolders,
 }) => {
   const [isOpen, setIsOpen] = useState(false);
+  
+  // Memoize click handlers to prevent recreation
+  const handlePlaylistClick = useCallback(() => {
+    onPlaylistSelect(node.name);
+  }, [onPlaylistSelect, node.name]);
+
+  const handleFolderToggle = useCallback(() => {
+    setIsOpen(prev => !prev);
+  }, []);
   const indent = level * 10; // Reverted back to 10px per level
 
   if (node.type === 'folder') {
@@ -86,8 +118,8 @@ const PlaylistItem: React.FC<PlaylistItemProps> = ({
         <Flex align="center" gap={1}>
           <Button
             flex={1}
-            {...getButtonStyles(false)}
-            onClick={() => setIsOpen(!isOpen)}
+            {...unselectedButtonStyles}
+            onClick={handleFolderToggle}
             ml={indent}
             pl={level > 0 ? 6 : 4} // Add extra padding for nested items
             justifyContent="flex-start"
@@ -154,8 +186,8 @@ const PlaylistItem: React.FC<PlaylistItemProps> = ({
     <Flex align="center" gap={0}>
       <Button
         flex="1 1 auto"
-        {...getButtonStyles(selectedItem === node.name)}
-        onClick={() => onPlaylistSelect(node.name)}
+        {...(selectedItem === node.name ? selectedButtonStyles : unselectedButtonStyles)}
+        onClick={handlePlaylistClick}
         ml={indent}
         pl={level > 0 ? 6 : 4} // Add extra padding for nested items
         borderRightRadius={0}
@@ -237,7 +269,7 @@ const PlaylistItem: React.FC<PlaylistItemProps> = ({
       </Menu>
     </Flex>
   );
-};
+});
 
 export const PlaylistManager: React.FC<PlaylistManagerProps> = ({
   playlists,
@@ -289,7 +321,7 @@ export const PlaylistManager: React.FC<PlaylistManagerProps> = ({
     <Box>
       <VStack spacing={2} align="stretch" mb={4}>
         <Button
-          {...getButtonStyles(selectedItem === null)}
+          {...(selectedItem === null ? selectedButtonStyles : unselectedButtonStyles)}
           onClick={() => onPlaylistSelect(null)}
         >
           All Songs

packages/frontend/src/hooks/usePaginatedSongs.ts

@@ -1,4 +1,4 @@
-import { useState, useEffect, useCallback, useRef } from 'react';
+import React, { useState, useEffect, useCallback, useRef } from 'react';
 import { api, type SongsResponse } from '../services/api';
 import type { Song } from '../types/interfaces';
 
@@ -125,9 +125,12 @@ export const usePaginatedSongs = (options: UsePaginatedSongsOptions = {}) => {
     setIsInitialLoad(true);
   }, [initialSearch, cleanup]);
 
-  // Initial load
+  // Initial load - only run once when the hook is first created
   useEffect(() => {
-    loadPage(1);
+    // Only load if we haven't loaded anything yet
+    if (songs.length === 0 && !loading) {
+      loadPage(1);
+    }
     
     // Cleanup on unmount
     return () => {
@@ -135,26 +138,27 @@ export const usePaginatedSongs = (options: UsePaginatedSongsOptions = {}) => {
     };
   }, []);
 
-  // Handle playlist changes
+  // Handle playlist changes - optimized for immediate response
   useEffect(() => {
-    if (!isInitialLoad && previousPlaylistRef.current !== playlistName) {
-      // Update refs
+    if (previousPlaylistRef.current !== playlistName) {
+      // Update refs immediately
       currentPlaylistRef.current = playlistName;
       currentSearchQueryRef.current = searchQuery;
       previousPlaylistRef.current = playlistName;
       
-      // Clear songs for new playlist to replace them
-      setSongs([]);
-      setHasMore(true);
-      setCurrentPage(1);
-      setSearchQuery(initialSearch);
-      setError(null);
-      // Use setTimeout to avoid the dependency issue
-      setTimeout(() => {
-        loadPage(1, initialSearch, playlistName);
-      }, 0);
+      // Batch all state updates together to reduce re-renders
+      React.startTransition(() => {
+        setSongs([]);
+        setHasMore(true);
+        setCurrentPage(1);
+        setSearchQuery(initialSearch);
+        setError(null);
+      });
+      
+      // Load immediately
+      loadPage(1, initialSearch, playlistName);
     }
-  }, [playlistName, isInitialLoad, initialSearch, loadPage]);
+  }, [playlistName, initialSearch, loadPage]);
 
   return {
     songs,