--- a/contrib/perf.py	Tue Jan 04 14:12:52 2011 -0600
+++ b/contrib/perf.py	Tue Jan 11 17:01:04 2011 -0600
@@ -81,8 +81,9 @@
 
 def perfindex(ui, repo):
     import mercurial.changelog
+    n = repo["tip"].node()
     def d():
-        t = repo.changelog.tip()
+        repo[n]
         repo.invalidate()
     timer(d)