Optimize autocomplete with debouncing

- Add 150ms debounce to text field onChange handler
- Prevents excessive autocomplete calculations during rapid typing
- Add timer cleanup in onDisappear
- Works for both main chat and private chat inputs

bitchat/ViewModels/ChatViewModel.swift

@@ -36,6 +36,11 @@ class ChatViewModel: ObservableObject {
     @Published var autocompleteRange: NSRange? = nil
     @Published var selectedAutocompleteIndex: Int = 0
     
+    // Autocomplete optimization
+    private let mentionRegex = try? NSRegularExpression(pattern: "@([a-zA-Z0-9_]*)$", options: [])
+    private var cachedNicknames: [String] = []
+    private var lastNicknameUpdate: Date = .distantPast
+    
     // Temporary property to fix compilation
     @Published var showPasswordPrompt = false
     
@@ -837,49 +842,76 @@ class ChatViewModel: ObservableObject {
     }
     
     func updateAutocomplete(for text: String, cursorPosition: Int) {
+        // Quick early exit for empty text
+        guard cursorPosition > 0 else {
+            if showAutocomplete {
+                showAutocomplete = false
+                autocompleteSuggestions = []
+                autocompleteRange = nil
+            }
+            return
+        }
+        
         // Find @ symbol before cursor
         let beforeCursor = String(text.prefix(cursorPosition))
         
-        // Look for @ pattern
+        // Use cached regex
-        let pattern = "@([a-zA-Z0-9_]*)$"
+        guard let regex = mentionRegex,
-        guard let regex = try? NSRegularExpression(pattern: pattern, options: []),
               let match = regex.firstMatch(in: beforeCursor, options: [], range: NSRange(location: 0, length: beforeCursor.count)) else {
-            showAutocomplete = false
+            if showAutocomplete {
-            autocompleteSuggestions = []
+                showAutocomplete = false
-            autocompleteRange = nil
+                autocompleteSuggestions = []
+                autocompleteRange = nil
+            }
             return
         }
         
         // Extract the partial nickname
         let partialRange = match.range(at: 1)
         guard let range = Range(partialRange, in: beforeCursor) else {
-            showAutocomplete = false
+            if showAutocomplete {
-            autocompleteSuggestions = []
+                showAutocomplete = false
-            autocompleteRange = nil
+                autocompleteSuggestions = []
+                autocompleteRange = nil
+            }
             return
         }
         
         let partial = String(beforeCursor[range]).lowercased()
         
-        // Get all available nicknames (excluding self)
+        // Update cached nicknames only if peer list changed (check every 1 second max)
-        let peerNicknames = meshService.getPeerNicknames()
+        let now = Date()
-        let allNicknames = Array(peerNicknames.values)
+        if now.timeIntervalSince(lastNicknameUpdate) > 1.0 || cachedNicknames.isEmpty {
+            let peerNicknames = meshService.getPeerNicknames()
+            cachedNicknames = Array(peerNicknames.values).sorted()
+            lastNicknameUpdate = now
+        }
         
-        // Filter suggestions
+        // Filter suggestions using cached nicknames
-        let suggestions = allNicknames.filter { nick in
+        let suggestions = cachedNicknames.filter { nick in
             nick.lowercased().hasPrefix(partial)
-        }.sorted()
+        }
         
+        // Batch UI updates
         if !suggestions.isEmpty {
-            autocompleteSuggestions = suggestions
+            // Only update if suggestions changed
-            showAutocomplete = true
+            if autocompleteSuggestions != suggestions {
-            autocompleteRange = match.range(at: 0) // Store full @mention range
+                autocompleteSuggestions = suggestions
+            }
+            if !showAutocomplete {
+                showAutocomplete = true
+            }
+            if autocompleteRange != match.range(at: 0) {
+                autocompleteRange = match.range(at: 0)
+            }
             selectedAutocompleteIndex = 0
         } else {
-            showAutocomplete = false
+            if showAutocomplete {
-            autocompleteSuggestions = []
+                showAutocomplete = false
-            autocompleteRange = nil
+                autocompleteSuggestions = []
-            selectedAutocompleteIndex = 0
+                autocompleteRange = nil
+                selectedAutocompleteIndex = 0
+            }
         }
     }
     

bitchat/Views/ContentView.swift

@@ -28,6 +28,7 @@ struct ContentView: View {
     @FocusState private var isNicknameFieldFocused: Bool
     @State private var lastScrollTime: Date = .distantPast
     @State private var scrollThrottleTimer: Timer?
+    @State private var autocompleteDebounceTimer: Timer?
     
     private var backgroundColor: Color {
         colorScheme == .dark ? Color.black : Color.white
@@ -159,6 +160,11 @@ struct ContentView: View {
             
             Button("cancel", role: .cancel) {}
         }
+        .onDisappear {
+            // Clean up timers
+            scrollThrottleTimer?.invalidate()
+            autocompleteDebounceTimer?.invalidate()
+        }
     }
     
     private func messagesView(privatePeer: String?) -> some View {
@@ -399,11 +405,17 @@ struct ContentView: View {
                 .focused($isTextFieldFocused)
                 .padding(.leading, 12)
                 .onChange(of: messageText) { newValue in
-                    // Get cursor position (approximate - end of text for now)
+                    // Cancel previous debounce timer
-                    let cursorPosition = newValue.count
+                    autocompleteDebounceTimer?.invalidate()
-                    viewModel.updateAutocomplete(for: newValue, cursorPosition: cursorPosition)
                     
-                    // Check for command autocomplete
+                    // Debounce autocomplete updates to reduce calls during rapid typing
+                    autocompleteDebounceTimer = Timer.scheduledTimer(withTimeInterval: 0.15, repeats: false) { _ in
+                        // Get cursor position (approximate - end of text for now)
+                        let cursorPosition = newValue.count
+                        viewModel.updateAutocomplete(for: newValue, cursorPosition: cursorPosition)
+                    }
+                    
+                    // Check for command autocomplete (instant, no debounce needed)
                     if newValue.hasPrefix("/") && newValue.count >= 1 {
                         // Build context-aware command list
                         let commandDescriptions = [