--- a/hgext/evolve.py	Fri Feb 06 17:01:28 2015 +0000
+++ b/hgext/evolve.py	Mon Mar 02 20:12:00 2015 +0100
@@ -2729,6 +2729,7 @@
 def _obsrelsethashtree(repo):
     cache = []
     unfi = repo.unfiltered()
+    markercache = {}
     for i in unfi:
         ctx = unfi[i]
         entry = 0
@@ -2745,7 +2746,11 @@
                 sha.update(p)
         tmarkers = repo.obsstore.relevantmarkers([ctx.node()])
         if tmarkers:
-            bmarkers = [obsolete._fm0encodeonemarker(m) for m in tmarkers]
+            bmarkers = []
+            for m in tmarkers:
+                if not m in markercache:
+                    markercache[m] = obsolete._fm0encodeonemarker(m)
+                bmarkers.append(markercache[m])
             bmarkers.sort()
             for m in bmarkers:
                 entry += 1