Documentation/public-inbox-tuning.pod | 11 +++++++----

diff --git a/Documentation/public-inbox-tuning.pod b/Documentation/public-inbox-tuning.pod
index 7b18b3bc403035e0eda5ab6dcb4d2059bdc3fb05..53668eccb7cb85a7a7c0f6149c0c8c54189614e2 100644
--- a/Documentation/public-inbox-tuning.pod
+++ b/Documentation/public-inbox-tuning.pod
@@ -165,12 +165,15 @@ Other OSes may have similar tuning knobs (patches appreciated).
 
 =head2 Scalability to many inboxes
 
+L<public-inbox-extindex(1)> allows any number of public-inboxes
+to share the same Xapian indices.
+
 git 2.33+ startup time is orders-of-magnitude faster and uses
 less memory when dealing with thousands of alternates required
-for thousands of inboxes.
+for thousands of inboxes with L<public-inbox-extindex(1)>.
 
-L<public-inbox-extindex(1)> allows any number of public-inboxes
-to share the same Xapian indices.
+Frequent packing (via L<git-gc(1)>) both improves performance
+and reduces the need to increase C<sys.vm.max_map_count>.
 
 =head1 CONTACT
 
@@ -184,6 +187,6 @@ L<http://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/meta/>, and other places
 
 =head1 COPYRIGHT
 
-Copyright 2020-2021 all contributors L<mailto:meta@public-inbox.org>
+Copyright all contributors L<mailto:meta@public-inbox.org>
 
 License: AGPL-3.0+ L<https://www.gnu.org/licenses/agpl-3.0.txt>