but only marginally faster in blead perl

From 5.30.0 perldelta:

Regular expression pattern matching of things like C<qr/[^I<a>]/> is
significantly sped up, where I<a> is any ASCII character.  Other class
+es
can get this speed up, but which ones is complicated and depends on th
+e
underlying bit patterns of those characters, so differs between ASCII
and EBCDIC platforms, but all case pairs, like C<qr/[Gg]/> are include
+d,
as is C<[^01]>.
[download]

Dave.