diff --git a/src/calibre/gui2/init.py b/src/calibre/gui2/init.py
index 27a6a2352a..fc70f0579d 100644
--- a/src/calibre/gui2/init.py
+++ b/src/calibre/gui2/init.py
@@ -123,6 +123,8 @@ class Stack(QStackedWidget): # {{{
                 _('Tag Browser'), I('tags.png'),
                 parent=parent, side_index=0, initial_side_size=200,
                 shortcut=_('Shift+Alt+T'))
+        parent.tb_splitter.state_changed.connect(
+                        self.tb_widget.set_pane_is_visible, Qt.QueuedConnection)
         parent.tb_splitter.addWidget(self.tb_widget)
         parent.tb_splitter.addWidget(parent.cb_splitter)
         parent.tb_splitter.setCollapsible(parent.tb_splitter.other_index, False)
diff --git a/src/calibre/gui2/tag_view.py b/src/calibre/gui2/tag_view.py
index 2ede698c85..d6c0156f13 100644
--- a/src/calibre/gui2/tag_view.py
+++ b/src/calibre/gui2/tag_view.py
@@ -87,6 +87,13 @@ class TagsView(QTreeView): # {{{
         self.setDragDropMode(self.DropOnly)
         self.setDropIndicatorShown(True)
         self.setAutoExpandDelay(500)
+        self.pane_is_visible = False
+
+    def set_pane_is_visible(self, to_what):
+        pv = self.pane_is_visible
+        self.pane_is_visible = to_what
+        if to_what and not pv:
+            self.recount()
 
     def set_database(self, db, tag_match, sort_by):
         self.hidden_categories = config['tag_browser_hidden_categories']
@@ -300,7 +307,7 @@ class TagsView(QTreeView): # {{{
         return self.isExpanded(idx)
 
     def recount(self, *args):
-        if self.disable_recounting:
+        if self.disable_recounting or not self.pane_is_visible:
             return
         self.refresh_signal_processed = True
         ci = self.currentIndex()
@@ -969,6 +976,7 @@ class TagBrowserWidget(QWidget): # {{{
         self._layout.setContentsMargins(0,0,0,0)
 
         parent.tags_view = TagsView(parent)
+        self.tags_view = parent.tags_view
         self._layout.addWidget(parent.tags_view)
 
         parent.sort_by = QComboBox(parent)
@@ -998,6 +1006,9 @@ class TagBrowserWidget(QWidget): # {{{
                 _('Add your own categories to the Tag Browser'))
         parent.edit_categories.setStatusTip(parent.edit_categories.toolTip())
 
+    def set_pane_is_visible(self, to_what):
+        self.tags_view.set_pane_is_visible(to_what)
+
 
 # }}}