diff --git a/cq_editor/widgets/viewer.py b/cq_editor/widgets/viewer.py
index 6fc6110e..05cdad12 100644
--- a/cq_editor/widgets/viewer.py
+++ b/cq_editor/widgets/viewer.py
@@ -306,12 +306,14 @@ def display(self, ais):
     def display_many(self, ais_list, fit=None):
         context = self._get_context()
         for ais in ais_list:
-            context.Display(ais, True)
+            context.Display(ais, False)
 
         if self.preferences["Fit automatically"] and fit is None:
             self.fit()
         elif fit:
             self.fit()
+        elif ais_list:
+            context.UpdateCurrentViewer()
 
     @pyqtSlot(QTreeWidgetItem, int)
     def update_item(self, item, col):
@@ -334,7 +336,9 @@ def remove_items(self, ais_items):
 
         ctx = self._get_context()
         for ais in ais_items:
-            ctx.Erase(ais, True)
+            ctx.Erase(ais, False)
+        if ais_items:
+            ctx.UpdateCurrentViewer()
 
     @pyqtSlot()
     def redraw(self):
diff --git a/tests/test_app.py b/tests/test_app.py
index dcc3d82c..76deda64 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -1,5 +1,6 @@
 from path import Path
 import os, sys, asyncio
+from time import perf_counter
 
 if sys.platform == "win32":
     asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
@@ -70,6 +71,19 @@
 code_nested_top = """import test_nested_bottom
 """
 
+code_many_shapes = """from cadquery.func import *
+
+num = 20
+
+for i in range(1, num + 1, 1):
+    for j in range(1, num + 1, 1):
+        globals()[f"b_{i}_{j}"] = box(1, 1, 1).move(
+            x=1.1 * i,
+            y=1.1 * j,
+            z=0,
+        )
+"""
+
 code_nested_bottom = """a=1
 """
 
@@ -272,6 +286,34 @@ def test_render(main):
     assert obj_tree_comp.CQ.childCount() == 3
 
 
+def test_many_shapes_render_and_erase_time(main_clean):
+    qtbot, win = main_clean
+
+    editor = win.components["editor"]
+    debugger = win.components["debugger"]
+    object_tree = win.components["object_tree"]
+    viewer = win.components["viewer"]
+
+    debugger.preferences["Reload CQ"] = False
+    object_tree.preferences["Clear all before each run"] = True
+    viewer.preferences["Fit automatically"] = True
+    editor.set_text(code_many_shapes)
+
+    start = perf_counter()
+    debugger._actions["Run"][0].triggered.emit()
+    render_elapsed = perf_counter() - start
+
+    assert object_tree.CQ.childCount() == 20 * 20
+
+    start = perf_counter()
+    object_tree.removeObjects()
+    erase_elapsed = perf_counter() - start
+
+    assert object_tree.CQ.childCount() == 0
+    assert render_elapsed < 2, f"400-shape render took {render_elapsed:.3f}s"
+    assert erase_elapsed < 2, f"400-shape erase took {erase_elapsed:.3f}s"
+
+
 def test_export(main, mocker):
 
     qtbot, win = main