-=item publicinbox.indexBatchSize
-
-Flushes changes to the filesystem and releases locks after
-indexing the given number of bytes. The default value of C<1m>
-(one megabyte) is low to minimize memory use and reduce
-contention with parallel invocations of L<public-inbox-mda(1)>,
-L<public-inbox-learn(1)>, and L<public-inbox-watch(1)>.
-
-Increase this value on powerful systems to improve throughput at
-the expense of memory use. The reduction of lock granularity
-may not be noticeable on fast systems.
+This influences memory usage of Xapian, but it is not exact.
+The actual memory used by Xapian and Perl has been observed
+in excess of 10x this value.