feat(perf): Implement Input Lag estimation logic

performance_monitor.py

@@ -13,6 +13,10 @@ class PerformanceMonitor:
         self._cpu_usage = 0.0
         self._cpu_lock = threading.Lock()
         
+        # Input lag tracking
+        self._last_input_time = None
+        self._input_lag_ms = 0.0
+        
         # Start CPU usage monitoring thread
         self._stop_event = threading.Event()
         self._cpu_thread = threading.Thread(target=self._monitor_cpu, daemon=True)
@@ -29,6 +33,9 @@ class PerformanceMonitor:
     def start_frame(self):
         self._start_time = time.time()
 
+    def record_input_event(self):
+        self._last_input_time = time.time()
+
     def end_frame(self):
         if self._start_time is None:
             return
@@ -37,6 +44,11 @@ class PerformanceMonitor:
         self._last_frame_time = (end_time - self._start_time) * 1000.0
         self._frame_count += 1
         
+        # Calculate input lag if an input occurred during this frame
+        if self._last_input_time is not None:
+            self._input_lag_ms = (end_time - self._last_input_time) * 1000.0
+            self._last_input_time = None
+        
         elapsed_since_fps = end_time - self._fps_last_time
         if elapsed_since_fps >= 1.0:
             self._fps = self._frame_count / elapsed_since_fps
@@ -50,7 +62,8 @@ class PerformanceMonitor:
         return {
             'last_frame_time_ms': self._last_frame_time,
             'fps': self._fps,
-            'cpu_percent': cpu_usage
+            'cpu_percent': cpu_usage,
+            'input_lag_ms': self._input_lag_ms
         }
 
     def stop(self):