=back
+Eliminated xhv_fill from struct xpvhv: This saves 1 IV per hash and on some
+systems will cause struct xpvhv to become cache aligned. To avoid this
+memory saving causing a slowdown elsewhere, boolean use of HvFILL now
+calls HvTOTALKEYS instead (which is equivalent) - so while the fill data when
+actually required is now calculated on demand, the cases when this needs to
+be done should be few and far between (f4431c .. fcd245).
+
=head1 Installation and Configuration Improvements
XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools