from perldoc perlre:

       WARNING: Once Perl sees that you need one of $&, $`, or $'
       anywhere in the program, it has to provide them for every
       pattern match.  This may substantially slow your program.
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In other words, you can use $& (i used to, im an ex-sed hacker), but it will slow things down and its kind of unmaintainable. $1 $2 $3 et cetera, are really shinier, happier codelets.

brother dep.

--
Laziness, Impatience, Hubris, and Generosity.