--- a/hgext3rd/evolve/stablerange.py	Fri Mar 24 03:22:56 2017 +0100
+++ b/hgext3rd/evolve/stablerange.py	Fri Mar 24 06:31:32 2017 +0100
@@ -167,6 +167,9 @@
         # the same for all ranges headed at the same merge. So we cache these
         # value to reuse them accross the same invocation.
         self._stablesortcache = {}
+        # something useful to compute the above
+        # mergerev -> stablesort, length
+        self._stablesortprepared = {}
         # if we already know all the revision that belong to a range, it is
         # quite trivial to have the subrange "inherit" that knowledge. This
         # cache is dedicated to hold the full list of revs inside a subrange
@@ -246,7 +249,10 @@
                 # call for the general case.
                 allrevs = self._stablesortcache.get(headrev)
                 if allrevs is None:
-                    allrevs = stablesort(repo, [headrev])
+                    allrevs = self._getrevsfrommerge(repo, headrev)
+                    if allrevs is None:
+                        allrevs = stablesort(repo, [headrev],
+                                             mergecallback=self._filestablesortcache)
                     self._stablesortcache[headrev] = allrevs
                 # takes from index
                 revs = allrevs[index:]
@@ -262,6 +268,37 @@
             self._parentscache[rev] = parents
         return parents
 
+    def _filestablesortcache(self, sortedrevs, merge):
+        if merge not in self._stablesortprepared:
+            self._stablesortprepared[merge] = (sortedrevs, len(sortedrevs))
+
+    def _getrevsfrommerge(self, repo, merge):
+        prepared = self._stablesortprepared.get(merge)
+        if prepared is None:
+            return None
+
+        mergedepth = self.depthrev(repo, merge)
+        allrevs = prepared[0][:prepared[1]]
+        nbextrarevs = prepared[1] - mergedepth
+        if not nbextrarevs:
+            return allrevs
+
+        anc = repo.changelog.ancestors([merge], inclusive=True)
+        top = []
+        counter = nbextrarevs
+        for rev in reversed(allrevs):
+            if rev in anc:
+                top.append(rev)
+            else:
+                counter -= 1
+                if counter <= 0:
+                    break
+
+        bottomidx = prepared[1] - (nbextrarevs + len(top))
+        revs = allrevs[:bottomidx]
+        revs.extend(reversed(top))
+        return revs
+
     @staticmethod
     def _depthmerge(cl, rev, p1, p2, stack, cache):
         # sub method to simplify the main 'depthrev' one