-It is generally not useful to specify higher values than the
-default due to contention in the top-level producer process.
+Another approach for HDDs is to use the
+L<public-inbox-index(1)/publicInbox.indexSequentialShard> option
+and many shards, so each shard may fit into the kernel page
+cache. Unfortunately, excessive shards slows down read-only
+query performance.
+
+For fast storage, it is generally not useful to specify higher
+values than the default due to the top-level producer process
+being a bottleneck.