diff --git a/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/cache/DesktopLocalCache.kt b/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/cache/DesktopLocalCache.kt
index 87128a75b..d1b9636a4 100644
--- a/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/cache/DesktopLocalCache.kt
+++ b/desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/cache/DesktopLocalCache.kt
@@ -85,8 +85,18 @@ class DesktopLocalCache : ICacheProvider {
     companion object {
     }
 
+    /** Index of notes by author pubkey — for fast metadata invalidation */
+    private val notesByAuthor = ConcurrentHashMap<HexKey, MutableSet<Note>>()
+
     val paymentTracker = NwcPaymentTracker()
 
+    private fun trackNoteAuthor(
+        note: Note,
+        authorPubkey: HexKey,
+    ) {
+        notesByAuthor.getOrPut(authorPubkey) { ConcurrentHashMap.newKeySet() }.add(note)
+    }
+
     // ----- User operations -----
 
     override fun getUserIfExists(pubkey: HexKey): User? = users.get(pubkey)
@@ -156,10 +166,9 @@ class DesktopLocalCache : ICacheProvider {
             if (newUserMetadata != null) {
                 user.updateUserInfo(newUserMetadata, event)
                 _metadataVersion.value++
-                // Invalidate metadata flows on notes by this author that have observers
-                // so QuotedNoteEmbed/FeedNoteCard recompose with updated avatar/name
-                notes.forEach { _, note ->
-                    if (note.author?.pubkeyHex == event.pubKey && note.flowSet?.metadata?.hasObservers() == true) {
+                // Invalidate metadata flows on notes by this author (O(K) via index)
+                notesByAuthor[event.pubKey]?.forEach { note ->
+                    if (note.flowSet?.metadata?.hasObservers() == true) {
                         note.flowSet?.metadata?.invalidateData()
                     }
                 }
@@ -245,6 +254,7 @@ class DesktopLocalCache : ICacheProvider {
         val author = getOrCreateUser(event.pubKey)
         val repliesTo = event.tagsWithoutCitations().map { getOrCreateNote(it) }
         note.loadEvent(event, author, repliesTo)
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
         repliesTo.forEach { it.addReply(note) }
         return true
@@ -263,6 +273,7 @@ class DesktopLocalCache : ICacheProvider {
         val author = getOrCreateUser(event.pubKey)
         val repliesTo = event.tagsWithoutCitations().map { getOrCreateNote(it) }
         note.loadEvent(event, author, repliesTo)
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
         repliesTo.forEach { it.addReply(note) }
         return true
@@ -283,6 +294,7 @@ class DesktopLocalCache : ICacheProvider {
             event.originalPost().mapNotNull { getNoteIfExists(it) } +
                 event.taggedAddresses().mapNotNull { addressableNotes.get(it.toValue()) }
         note.loadEvent(event, author, reactedTo)
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
         reactedTo.forEach { it.addReaction(note) }
         return true
@@ -300,6 +312,7 @@ class DesktopLocalCache : ICacheProvider {
         if (note.event != null) return false
         val author = getOrCreateUser(event.pubKey)
         note.loadEvent(event, author, emptyList())
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
         return true
     }
@@ -331,6 +344,7 @@ class DesktopLocalCache : ICacheProvider {
                 event.taggedAddresses().mapNotNull { addressableNotes.get(it.toValue()) }
 
         note.loadEvent(event, author, zappedNotes)
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
 
         // Link zap to target notes
@@ -358,6 +372,7 @@ class DesktopLocalCache : ICacheProvider {
         val boostedNote = boostedId?.let { getOrCreateNote(it) }
         val repliesTo = listOfNotNull(boostedNote)
         note.loadEvent(event, author, repliesTo)
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
         boostedNote?.addBoost(note)
         return true
@@ -377,6 +392,7 @@ class DesktopLocalCache : ICacheProvider {
         val boostedNote = event.boostedEventId()?.let { getOrCreateNote(it) }
         val repliesTo = listOfNotNull(boostedNote)
         note.loadEvent(event, author, repliesTo)
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
         boostedNote?.addBoost(note)
         return true
@@ -408,6 +424,7 @@ class DesktopLocalCache : ICacheProvider {
         if (note.event != null) return false
         val author = getOrCreateUser(event.pubKey)
         note.loadEvent(event, author, emptyList())
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
         return true
     }
@@ -467,6 +484,7 @@ class DesktopLocalCache : ICacheProvider {
         if (note.event != null) return false
 
         note.loadEvent(event, author, emptyList())
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
 
         zappedNote?.addZapPayment(note, null)
@@ -498,6 +516,7 @@ class DesktopLocalCache : ICacheProvider {
         if (note.event != null) return false
 
         note.loadEvent(event, author, emptyList())
+        trackNoteAuthor(note, event.pubKey)
         relay?.let { note.addRelay(it) }
 
         // Link response to zapped note via request
@@ -617,6 +636,7 @@ class DesktopLocalCache : ICacheProvider {
         _followedUsers.value = emptySet()
         followerCounts.clear()
         followingCounts.clear()
+        notesByAuthor.clear()
         lastContactListCreatedAt = 0L
     }
 }