diff -r 1d118f9f4f57 -r 4fb2bb61597c mercurial/bundle2.py
--- a/mercurial/bundle2.py	Mon Jan 22 12:23:47 2018 -0800
+++ b/mercurial/bundle2.py	Sat Jan 20 22:55:42 2018 -0800
@@ -183,7 +183,7 @@
 _fpayloadsize = '>i'
 _fpartparamcount = '>BB'
 
-preferedchunksize = 4096
+preferedchunksize = 32768
 
 _parttypeforbidden = re.compile('[^a-zA-Z0-9_:-]')