http://www.perlmonks.org?node_id=840754


in reply to Re: Unefficient Regexp 'Matching this or that'
in thread Unefficient Regexp 'Matching this or that'

I think this case got a heavy speed up in 5.10.

Not in all cases. See Re: Unefficient Regexp 'Matching this or that'. For low and high numbers of alternations, it is actually a pessimisation.