1 files changed, 8 insertions, 2 deletions
diff --git a/vquad/core.py b/vquad/core.py
index 7f586f9..23f1c24 100644
--- a/vquad/core.py
+++ b/vquad/core.py
@@ -3,6 +3,8 @@
 # This file is part of Vquad.  It is subject to the license terms in the file
 # LICENSE.rst found in the top-level directory of this distribution.
 
+from bisect import insort
+
 import numpy as np
 from scipy.linalg import norm
 
@@ -193,8 +195,12 @@ class Vquad:
                 return
 
         if split:
-            self.ivals.extend(self.split(self.ivals.pop()))
-        self.ivals.sort()
+            # Replace current interval by its children.
+            for new in self.split(self.ivals.pop()):
+                insort(self.ivals, new)
+        else:
+            # The error estimate of the current interval has changed.
+            insort(self.ivals, self.ivals.pop())
 
     def totals(self):
         igral = self.igral_excess