diff --git a/hgext3rd/perftweaks.py b/hgext3rd/perftweaks.py
--- a/hgext3rd/perftweaks.py
+++ b/hgext3rd/perftweaks.py
@@ -36,6 +36,7 @@
     wrapfunction(tags, '_readtagcache', _readtagcache)
     wrapfunction(merge, '_checkcollision', _checkcollision)
     wrapfunction(branchmap.branchcache, 'update', _branchmapupdate)
+    wrapfunction(branchmap, 'updatecache', _branchmapupdatecache)
     if ui.configbool('perftweaks', 'preferdeltas'):
         wrapfunction(revlog.revlog, '_isgooddelta', _isgooddelta)
 
@@ -111,6 +112,16 @@
     repo.ui.log('branchcache', 'perftweaks updated %s branch cache\n',
                 repo.filtername)
 
+def _branchmapupdatecache(orig, repo):
+    if not repo.ui.configbool('perftweaks', 'disablebranchcache'):
+        return orig(repo)
+
+    filtername = repo.filtername
+    if filtername not in repo._branchcaches:
+        cache = branchmap.branchcache()
+        _branchmapupdate(None, cache, repo, None)
+        repo._branchcaches[filtername] = cache
+
 def _branchmapwrite(orig, self, repo):
     result = orig(self, repo)
     if repo.ui.configbool('perftweaks', 'cachenoderevs', True):