leedo/Plack-App-Proxy — pull request #12 by hiratara (2014-04-01 02:40:52+00:00)
Title: Avoid global performance penalty by using $&

We shouldn't use $& in our codes.

http://perldoc.perl.org/perlvar.html

> The use of this variable anywhere in a program imposes a considerable performance penalty on all regular expression matches.