Variable Explorer: Don't refresh it after giving focus to it

Fixes #2593

spyderlib/widgets/externalshell/namespacebrowser.py

@@ -249,14 +249,23 @@ def option_changed(self, option, value):
             settings = self.get_view_settings()
             communicate(self._get_sock(),
                         'set_remote_view_settings()', settings=[settings])
-        
+
     def visibility_changed(self, enable):
-        """Notify the widget whether its container (the namespace browser 
+        """Notify the widget whether its container (the namespace browser
         plugin is visible or not"""
-        self.is_visible = enable
-        if enable:
-            self.refresh_table()
-
+        # This is slowing down Spyder a lot if too much data is present in
+        # the Variable Explorer, and users give focus to it after being hidden.
+        # This also happens when the Variable Explorer is visible and users
+        # give focus to Spyder after using another application (like Chrome
+        # or Firefox).
+        # That's why we've decided to remove this feature
+        # Fixes Issue 2593
+        #
+        # self.is_visible = enable
+        # if enable:
+        #     self.refresh_table()
+        pass
+
     def toggle_auto_refresh(self, state):
         """Toggle auto refresh state"""
         self.autorefresh = state