chore(messages): remove temporary [PERF] instrumentation

On-device capture confirmed the fix (cold-boot tap: fallbacks=0,
gather=2ms, total=48ms vs 2086ms pre-fix; repeat taps no longer
perpetually fall back). All [PERF] timing markers and stage
variables are removed from refresh()/show()/render_route; the
branch is now clean of diagnostic code.

lib/tdeck_ui/UI/LXMF/ConversationListScreen.cpp

@@ -198,13 +198,6 @@ void ConversationListScreen::refresh() {
         return;
     }
 
-    // [PERF] temporary instrumentation — removable. Stage timings for the
-    // Messages tap path. Kept as INFO so it survives a DEBUG-off build and
-    // lands in the serial capture.
-    const uint32_t p_t0 = millis();
-    uint32_t p_t_gather = 0, p_t_diff = 0, p_t_rebuild = 0;
-    size_t p_fallbacks = 0;
-
     // Revalidate-then-render: gather the row data first (now O(1) per
     // conversation — index preview + hash + unread, no message-file I/O)
     // and compare it against what is already on screen. The old path
@@ -256,7 +249,6 @@ void ConversationListScreen::refresh() {
             _message_store->get_last_message_preview(peer_hash, preview, preview_ts);
         bool need_metadata = !have_preview;
         bool queued_drops = false;
-        if (need_metadata) p_fallbacks++;
 
         ::LXMF::MessageStore::MessageMetadata last_meta;
         last_meta.valid = false;
@@ -391,7 +383,6 @@ void ConversationListScreen::refresh() {
     // BEFORE any later refresh takes the lock, so a refresh in that
     // window sees the data unchanged (badge stays off) and the first
     // refresh after the flush sees unread==0 and rebuilds correctly.)
-    p_t_gather = millis() - p_t0;
     bool changed = (gathered.size() != _conversations.size());
     if (!changed) {
         for (size_t i = 0; i < gathered.size(); ++i) {
@@ -407,15 +398,7 @@ void ConversationListScreen::refresh() {
             }
         }
     }
-    p_t_diff = millis() - p_t0;
     if (!changed) {
-        // [PERF] temporary instrumentation — removable.
-        char perf_buf[128];
-        snprintf(perf_buf, sizeof(perf_buf),
-            "[PERF] convlist skip rows=%u fallbacks=%u gather=%ums diff=%ums total=%ums",
-            (unsigned)gathered.size(), (unsigned)p_fallbacks,
-            (unsigned)p_t_gather, (unsigned)p_t_diff, (unsigned)p_t_diff);
-        INFO(perf_buf);
         return;  // rows on screen are current
     }
 
@@ -435,7 +418,6 @@ void ConversationListScreen::refresh() {
         _conversations.push_back(item);
         create_conversation_item(item);
     }
-    p_t_rebuild = millis() - p_t0;
 
     // refresh() may run while Messages remains active. Newly created rows are
     // not automatically restored to the encoder group after lv_obj_clean().
@@ -447,16 +429,6 @@ void ConversationListScreen::refresh() {
             }
         }
     }
-
-    // [PERF] temporary instrumentation — removable.
-    {
-        char perf_buf[128];
-        snprintf(perf_buf, sizeof(perf_buf),
-            "[PERF] convlist build rows=%u fallbacks=%u gather=%ums rebuild=%ums total=%ums",
-            (unsigned)gathered.size(), (unsigned)p_fallbacks,
-            (unsigned)p_t_gather, (unsigned)p_t_rebuild, (unsigned)(millis() - p_t0));
-        INFO(perf_buf);
-    }
 }
 
 void ConversationListScreen::flush_pending_name_writes() {
@@ -655,8 +627,6 @@ void ConversationListScreen::set_home_callback(HomeCallback callback) {
 
 void ConversationListScreen::show() {
     LVGL_LOCK();
-    // [PERF] temporary instrumentation — removable.
-    const uint32_t p_show_start = millis();
     _visible = true;
     lv_obj_clear_flag(_screen, LV_OBJ_FLAG_HIDDEN);
     lv_obj_move_foreground(_screen);  // Bring to front for touch events
@@ -684,14 +654,6 @@ void ConversationListScreen::show() {
             lv_group_focus_obj(_btn_new);
         }
     }
-
-    // [PERF] temporary instrumentation — removable.
-    {
-        char perf_buf[64];
-        snprintf(perf_buf, sizeof(perf_buf), "[PERF] convlist show=%ums",
-            (unsigned)(millis() - p_show_start));
-        INFO(perf_buf);
-    }
 }
 
 void ConversationListScreen::hide() {

lib/tdeck_ui/UI/LXMF/UIManager.cpp

@@ -1118,19 +1118,12 @@ void UIManager::render_route(Route route) {
         case Route::HOME:
             _home_screen->show();
             break;
-        case Route::MESSAGES: {
-            // [PERF] temporary instrumentation — removable.
-            const uint32_t p_route_start = millis();
+        case Route::MESSAGES:
             _conversation_list_screen->refresh();
             _pending_conversation_refresh = false;
             _last_conversation_refresh_ms = millis();
             _conversation_list_screen->show();
-            char perf_buf[64];
-            snprintf(perf_buf, sizeof(perf_buf), "[PERF] convlist route=%ums",
-                (unsigned)(millis() - p_route_start));
-            INFO(perf_buf);
             break;
-        }
         case Route::MAP:
             _map_screen->show();
             break;