diff --git a/hgext3rd/perftweaks.py b/hgext3rd/perftweaks.py
--- a/hgext3rd/perftweaks.py
+++ b/hgext3rd/perftweaks.py
@@ -12,6 +12,9 @@
     # Whether to use faster hidden cache. It has faster cache hash calculation
     # which only check stat of a few files inside store/ directory.
     fasthiddencache = False
+
+    # Reorder namespaces so "branches" and "tags" are at the last.
+    reordernamespaces = True
 """
 
 from mercurial import (
@@ -19,6 +22,7 @@
     dispatch,
     extensions,
     merge,
+    namespaces,
     phases,
     revlog,
     scmutil,
@@ -65,10 +69,26 @@
     except KeyError:
         pass
 
+    wrapfunction(namespaces.namespaces, 'singlenode', _singlenode)
+
 def reposetup(ui, repo):
     if repo.local() is not None:
         _preloadrevs(repo)
 
+def _singlenode(orig, self, repo, name):
+    """Skips reading tags or namespaces if unnecessary"""
+    names = self._names
+    namesbak = names.copy()
+    # branches only makes sense if name == 'default'.
+    # Loading 'branches' requires O(len(changelog)) time complexity because
+    # it calls headrevs() which scans the entire changelog.
+    if name != 'default' and 'branches' in names:
+        del names['branches']
+    try:
+        return orig(self, repo, name)
+    finally:
+        self.names = namesbak
+
 def _readtagcache(orig, ui, repo):
     """Disables reading tags if the repo is known to not contain any."""
     if ui.configbool('perftweaks', 'disabletags'):
@@ -201,6 +221,16 @@
 def _cachefilename(name):
     return 'noderevs/%s' % name
 
+def _namesiteritems(orig):
+    buffered = []
+    for k, v in orig():
+        if k in ('tags', 'branches'):
+            buffered.append((k, v))
+        else:
+            yield k, v
+    for k, v in buffered:
+        yield k, v
+
 def _preloadrevs(repo):
     # Preloading the node-rev map for likely to be used revs saves 100ms on
     # every command. This is because normally to look up a node, hg has to scan