perf: eliminate N+1 getNoteAllUsers calls and merge loadSettings+loadNotes to fix double-render cascade

- Skip getNoteAllUsers server action for for own notes (majority of notes), Only fetch collaborators for shared notes.
- Merge loadSettings and loadNotes into single useEffect to prevent double loadNotes trigger when showRecentNotes state changes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

keep-notes/app/(main)/page.tsx

@@ -152,23 +152,20 @@ export default function HomePage() {
   // Enable reminder notifications
   useReminderCheck(notes)
 
-  // Load user settings to check if recent notes should be shown
+  // Load settings + notes in a single effect to avoid cascade re-renders
   useEffect(() => {
-    const loadSettings = async () => {
+    const load = async () => {
+      // Load settings first
+      let showRecent = true
       try {
         const settings = await getAISettings()
-        // Default to true if setting is undefined or null
-        setShowRecentNotes(settings?.showRecentNotes !== false)
+        showRecent = settings?.showRecentNotes !== false
       } catch (error) {
         // Default to true on error
-        setShowRecentNotes(true)
       }
-    }
-    loadSettings()
-  }, [refreshKey])
+      setShowRecentNotes(showRecent)
 
-  useEffect(() => {
-    const loadNotes = async () => {
+      // Then load notes
       setIsLoading(true)
       const search = searchParams.get('search')?.trim() || null
       const semanticMode = searchParams.get('semantic') === 'true'
@@ -214,7 +211,7 @@ export default function HomePage() {
       setPinnedNotes(pinnedFilter)
 
       // Derive recent notes from already-fetched allNotes (no extra server call)
-      if (showRecentNotes) {
+      if (showRecent) {
         const sevenDaysAgo = new Date()
         sevenDaysAgo.setDate(sevenDaysAgo.getDate() - 7)
         sevenDaysAgo.setHours(0, 0, 0, 0)
@@ -240,9 +237,9 @@ export default function HomePage() {
       setIsLoading(false)
     }
 
-    loadNotes()
+    load()
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [searchParams, refreshKey, showRecentNotes]) // Intentionally omit 'labels' and 'semantic' to prevent reload when adding tags or from router.push
+  }, [searchParams, refreshKey]) // Intentionally omit 'labels' to prevent reload when adding tags
   // Get notebooks context to display header
   const { notebooks } = useNotebooks()
   const currentNotebook = notebooks.find((n: any) => n.id === searchParams.get('notebook'))

keep-notes/components/note-card.tsx

@@ -184,17 +184,30 @@ export const NoteCard = memo(function NoteCard({
   const isSharedNote = currentUserId && note.userId && currentUserId !== note.userId
   const isOwner = currentUserId && note.userId && currentUserId === note.userId
 
-  // Load collaborators when note changes
+  // Load collaborators only for shared notes (not owned by current user)
   useEffect(() => {
+    // Skip API call for notes owned by current user — no need to fetch collaborators
+    if (!isSharedNote) {
+      // For own notes, set owner to current user
+      if (currentUserId && session?.user) {
+        setOwner({
+          id: currentUserId,
+          name: session.user.name,
+          email: session.user.email,
+          image: session.user.image,
+        })
+      }
+      return
+    }
+
     let isMounted = true
-    
+
     const loadCollaborators = async () => {
       if (note.userId && isMounted) {
         try {
           const users = await getNoteAllUsers(note.id)
           if (isMounted) {
             setCollaborators(users)
-            // Owner is always first in the list
             if (users.length > 0) {
               setOwner(users[0])
             }
@@ -209,11 +222,11 @@ export const NoteCard = memo(function NoteCard({
     }
 
     loadCollaborators()
-    
+
     return () => {
       isMounted = false
     }
-  }, [note.id, note.userId])
+  }, [note.id, note.userId, isSharedNote, currentUserId, session?.user])
 
   const handleDelete = async () => {
     if (confirm(t('notes.confirmDelete'))) {