feat(perf): Add performance tests and high-precision timing

src/performance_monitor.py

@@ -154,7 +154,7 @@ class PerformanceMonitor:
    return self._history_sums[key] / len(h)
 
  def start_frame(self) -> None:
-  now = time.time()
+  now = time.perf_counter()
   with self._lock:
    if self._last_frame_start_time > 0:
     dt = now - self._last_frame_start_time
@@ -167,7 +167,7 @@ class PerformanceMonitor:
  def end_frame(self) -> None:
   if self._start_time is None:
    return
-  now = time.time()
+  now = time.perf_counter()
   elapsed = now - self._start_time
   frame_time_ms = elapsed * 1000
   
@@ -194,13 +194,13 @@ class PerformanceMonitor:
 
  def start_component(self, name: str) -> None:
   if not self.enabled: return
-  now = time.time()
+  now = time.perf_counter()
   with self._lock:
    self._component_starts[name] = now
 
  def end_component(self, name: str) -> None:
   if not self.enabled: return
-  now = time.time()
+  now = time.perf_counter()
   with self._lock:
    start = self._component_starts.pop(name, None)
   if start is not None: