diff --git a/vnpy/chart/item.py b/vnpy/chart/item.py
index e04c7643..c63adee3 100644
--- a/vnpy/chart/item.py
+++ b/vnpy/chart/item.py
@@ -32,6 +32,8 @@ class ChartItem(pg.GraphicsObject):
         )
         self._down_brush: QtGui.QBrush = pg.mkBrush(color=DOWN_COLOR)
 
+        self._rect_area: Tuple[float, float] = None
+
     @abstractmethod
     def _draw_bar_picture(self, ix: int, bar: BarData) -> QtGui.QPicture:
         """
@@ -109,7 +111,11 @@ class ChartItem(pg.GraphicsObject):
         min_ix = int(rect.left())
         max_ix = int(rect.right())
         max_ix = min(max_ix, len(self._bar_picutures))
-        self._draw_item_picture(min_ix, max_ix)
+
+        rect_area = (rect.left(), rect.right())
+        if rect_area != self._rect_area or not self._item_picuture:
+            self._rect_area = rect_area
+            self._draw_item_picture(min_ix, max_ix)
 
         self._item_picuture.play(painter)
 
diff --git a/vnpy/chart/manager.py b/vnpy/chart/manager.py
index a786eed6..d4beda07 100644
--- a/vnpy/chart/manager.py
+++ b/vnpy/chart/manager.py
@@ -118,6 +118,7 @@ class BarManager:
             max_price = max(max_price, bar.high_price)
             min_price = min(min_price, bar.low_price)
 
+        self._price_ranges[(min_ix, max_ix)] = (min_price, max_price)
         return min_price, max_price
 
     def get_volume_range(self, min_ix: float = None, max_ix: float = None) -> Tuple[float, float]:
@@ -148,6 +149,7 @@ class BarManager:
         for bar in bar_list[1:]:
             max_volume = max(max_volume, bar.volume)
 
+        self._volume_ranges[(min_ix, max_ix)] = (min_volume, max_volume)
         return min_volume, max_volume
 
     def _clear_cache(self) -> None:
diff --git a/vnpy/chart/widget.py b/vnpy/chart/widget.py
index e00aab1b..caf4c8a9 100644
--- a/vnpy/chart/widget.py
+++ b/vnpy/chart/widget.py
@@ -399,7 +399,8 @@ class ChartCursor(QtCore.QObject):
         """
         self._proxy = pg.SignalProxy(
             self._widget.scene().sigMouseMoved,
-            rateLimit=360,
+            delay=0.1,
+            rateLimit=60,
             slot=self._mouse_moved
         )
 
@@ -412,6 +413,7 @@ class ChartCursor(QtCore.QObject):
 
         # First get current mouse point
         pos = evt[0]
+
         for plot_name, view in self._views.items():
             rect = view.sceneBoundingRect()