--- a/mercurial/configitems.py	Fri Jun 22 17:12:24 2018 +0200
+++ b/mercurial/configitems.py	Tue Jul 10 02:33:43 2018 +0200
@@ -597,7 +597,7 @@
     default=0.50,
 )
 coreconfigitem('experimental', 'sparse-read.min-gap-size',
-    default='256K',
+    default='65K',
 )
 coreconfigitem('experimental', 'treemanifest',
     default=False,