diff --git a/hgext3rd/perftweaks.py b/hgext3rd/perftweaks.py
--- a/hgext3rd/perftweaks.py
+++ b/hgext3rd/perftweaks.py
@@ -79,6 +79,27 @@
     if repo.local() is not None:
         _preloadrevs(repo)
 
+        # developer config: perftweaks.disableupdatebranchcacheoncommit
+        if repo.ui.configbool('perftweaks', 'disableupdatebranchcacheoncommit'):
+            class perftweaksrepo(repo.__class__):
+                @localrepo.unfilteredmethod
+                def updatecaches(self, tr=None):
+                    # Disable "branchmap.updatecache(self.filtered('served'))"
+                    # code path guarded by "if tr.changes['revs']". First, we
+                    # don't have on-disk branchmap. Second, accessing
+                    # "repo.filtered('served')" alone is not very cheap.
+                    bakrevs = None
+                    if tr and 'revs' in tr.changes:
+                        bakrevs = tr.changes['revs']
+                        tr.changes['revs'] = frozenset()
+                    try:
+                        super(perftweaksrepo, self).updatecaches(tr)
+                    finally:
+                        if bakrevs:
+                            tr.changes['revs'] = bakrevs
+
+            repo.__class__ = perftweaksrepo
+
 def _singlenode(orig, self, repo, name):
     """Skips reading branches namespace if unnecessary"""
     # developer config: perftweaks.disableresolvingbranches
diff --git a/tests/test-perftweaks.t b/tests/test-perftweaks.t
--- a/tests/test-perftweaks.t
+++ b/tests/test-perftweaks.t
@@ -120,6 +120,23 @@
   $ echo D > D
   $ hg commit -m D -A D --config perftweaks.disableheaddetection=1
 
+Test disabling updating branchcache during commit
+
+  $ $TESTDIR/ls-l.py .hg/cache | grep branch
+  -rw-r--r--     196 branch2-served
+
+  $ rm -f .hg/cache/branch*
+  $ echo D >> D
+  $ hg commit -m D2
+  $ $TESTDIR/ls-l.py .hg/cache | grep branch
+  -rw-r--r--     196 branch2-served
+
+  $ rm -f .hg/cache/branch*
+  $ echo D >> D
+  $ hg commit -m D3 --config perftweaks.disableupdatebranchcacheoncommit=1 --config perftweaks.disableheaddetection=1
+  $ $TESTDIR/ls-l.py .hg/cache | grep branch
+  [1]
+
   $ cd ..
 
 Test changing the delta heuristic