B<Note:> Much code exists that works around perl's historic poor
performance on alternations. Often the tricks used to do so will disable
the new optimisations. Hopefully the utility modules used for this purpose
-will be educated about these new optimisations by the time 5.10 is
-released.
+will be educated about these new optimisations.
=item Aho-Corasick start-point optimisation
=head1 Changed Internals
-In general, the source code of perl has been refactored, tied up, and
-optimized in many places. Also, memory management and allocation has been
-improved in a couple of points.
+In general, the source code of perl has been refactored, tidied up,
+and optimized in many places. Also, memory management and allocation
+has been improved in several points.
+
+When compiling the perl core with gcc, as many gcc warning flags are
+turned on as is possible on the platform. (This quest for cleanliness
+doesn't extend to XS code because we cannot guarantee the tidiness of
+code we didn't write.) Similar strictness flags have been added or
+tightened for various other C compilers.
=head2 Reordering of SVt_* constants