Fixes issue #6838: use a list to accumulate the value instead of repeatedly concatenating strings.
diff --git a/Misc/NEWS b/Misc/NEWS
index bc7f5b0..f0a714c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -68,6 +68,11 @@
 Library
 -------
 
+- Issue #6838: Use a list to accumulate the value instead of
+  repeatedly concatenating strings in http.client's
+  HTTPResponse._read_chunked providing a significant speed increase
+  when downloading large files servend with a Transfer-Encoding of 'chunked'.
+
 - Trying to import a submodule from a module that is not a package, ImportError
   should be raised, not AttributeError.