Keeps Note level in a thread cached for ordering notes.

app/src/main/java/com/vitorpamplona/amethyst/model/Note.kt

@@ -73,25 +73,30 @@ class Note(val idHex: String) {
             .format(DateTimeFormatter.ofPattern("uuuu-MM-dd-HH:mm:ss"))
     }
 
-    fun replyLevelSignature(): String {
+    /**
+     * This method caches signatures during each execution to avoid recalculation in longer threads
+     */
+    fun replyLevelSignature(cachedSignatures: MutableMap<Note, String> = mutableMapOf()): String {
         val replyTo = replyTo
         if (replyTo == null || replyTo.isEmpty()) {
             return "/" + formattedDateTime(event?.createdAt ?: 0) + ";"
         }
 
         return replyTo
-            .map { it.replyLevelSignature() }
+            .map {
+                cachedSignatures[it] ?: it.replyLevelSignature(cachedSignatures).apply { cachedSignatures.put(it, this) }
+            }
             .maxBy { it.length }.removeSuffix(";") + "/" + formattedDateTime(event?.createdAt ?: 0) + ";"
     }
 
-    fun replyLevel(): Int {
+    fun replyLevel(cachedLevels: MutableMap<Note, Int> = mutableMapOf()): Int {
         val replyTo = replyTo
         if (replyTo == null || replyTo.isEmpty()) {
             return 0
         }
 
         return replyTo.maxOf {
-            it.replyLevel()
+            cachedLevels[it] ?: it.replyLevel(cachedLevels).apply { cachedLevels.put(it, this) }
         } + 1
     }
 

app/src/main/java/com/vitorpamplona/amethyst/ui/dal/ThreadFeedFilter.kt

@@ -9,9 +9,10 @@ object ThreadFeedFilter: FeedFilter<Note>() {
   var noteId: String? = null
 
   override fun feed(): List<Note> {
+    val cachedSignatures: MutableMap<Note, String> = mutableMapOf()
     val eventsToWatch = noteId?.let { ThreadAssembler().findThreadFor(it) } ?: emptySet()
     // Currently orders by date of each event, descending, at each level of the reply stack
-    val order = compareByDescending<Note> { it.replyLevelSignature() }
+    val order = compareByDescending<Note> { it.replyLevelSignature(cachedSignatures) }
 
     return eventsToWatch.sortedWith(order)
   }

app/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/ThreadScreen.kt

@@ -26,11 +26,11 @@ fun ThreadScreen(noteId: String?, accountViewModel: AccountViewModel, navControl
     val lifeCycleOwner = LocalLifecycleOwner.current
 
     if (account != null && noteId != null) {
-        ThreadFeedFilter.loadThread(noteId)
-        NostrThreadDataSource.loadThread(noteId)
         val feedViewModel: NostrThreadFeedViewModel = viewModel()
 
         LaunchedEffect(Unit) {
+            ThreadFeedFilter.loadThread(noteId)
+            NostrThreadDataSource.loadThread(noteId)
             feedViewModel.invalidateData()
         }