diff --git a/hgext3rd/perftweaks.py b/hgext3rd/perftweaks.py
--- a/hgext3rd/perftweaks.py
+++ b/hgext3rd/perftweaks.py
@@ -16,8 +16,10 @@
 
 from mercurial import (
     branchmap,
+    commands,
     dispatch,
     extensions,
+    localrepo,
     merge,
     namespaces,
     obsutil,
@@ -41,6 +43,7 @@
     wrapfunction(branchmap, 'read', _branchmapread)
     wrapfunction(branchmap, 'replacecache', _branchmapreplacecache)
     wrapfunction(branchmap, 'updatecache', _branchmapupdatecache)
+    wrapfunction(commands, '_docommit', _docommit)
     if ui.configbool('perftweaks', 'preferdeltas'):
         wrapfunction(revlog.revlog, '_isgooddelta', _isgooddelta)
 
@@ -162,6 +165,22 @@
     partial.update(repo, None)
     repo._branchcaches[repo.filtername] = partial
 
+# _docommit accesses "branchheads" just to decide whether to show "(created new
+# head)" or not. Accessing branchheads requires calling "headrevs()" which is
+# expensive since it scans entire changelog. We don't use named branches and
+# do not worry about multiple heads.
+def _docommit(orig, ui, repo, *pats, **opts):
+    # developer config: perftweaks.disableheaddetection
+    if not repo.ui.configbool('perftweaks', 'disableheaddetection'):
+        return orig(ui, repo, *pats, **opts)
+
+    def _fakedbranchheads(orig, repo, *args, **kwargs):
+        # Make "." a "head" so the "created new head" message won't be printed.
+        return [repo['.'].node()]
+    with extensions.wrappedfunction(localrepo.localrepository,
+                                    'branchheads', _fakedbranchheads):
+        return orig(ui, repo, *pats, **opts)
+
 def _branchmapwrite(orig, self, repo):
     if repo.ui.configbool('perftweaks', 'disablebranchcache2'):
         # Since we don't read the branchcache, don't bother writing it.
diff --git a/tests/test-perftweaks.t b/tests/test-perftweaks.t
--- a/tests/test-perftweaks.t
+++ b/tests/test-perftweaks.t
@@ -1,5 +1,6 @@
   $ cat >> $HGRCPATH << EOF
   > [extensions]
+  > drawdag=$RUNTESTDIR/drawdag.py
   > perftweaks=$TESTDIR/../hgext3rd/perftweaks.py
   > EOF
 
@@ -102,6 +103,25 @@
 
   $ cd ..
 
+Test avoiding calculating head changes during commit
+
+  $ hg init branchatcommit
+  $ cd branchatcommit
+  $ hg debugdrawdag<<'EOS'
+  > B
+  > |
+  > A
+  > EOS
+  $ hg up -q A
+  $ echo C > C
+  $ hg commit -m C -A C
+  created new head
+  $ hg up -q A
+  $ echo D > D
+  $ hg commit -m D -A D --config perftweaks.disableheaddetection=1
+
+  $ cd ..
+
 Test changing the delta heuristic
 (this isn't a good test, but it executes the code path)
   $ hg init preferdeltaserver