Performance issue due to $&

I was looking through a coworker's regex book and the Perl chapter has 
section on performance problems caused by $&. If $& or $` are used by any 
module whatsoever, all perl regex matches in the entire program make an 
extra copy of the string regardless of whether it is needed or not. This 
causes a severe, but hidden performance penalty that is up to 5x for simple 
regexes that I verified and which was caused by Message::Head::Complete. 
This is particularly painful for Mail::Box because it manipulates large 
RFC822 message text

Can you replace $& in Message::Head::Complete, 
Message::TransferEnc::SevenBit, IMAPClient::Thread and 
IMAPClient::BodyStructure::Parse. It should help some performance and memory 
issues that people have noticed

Thanks,
    Todd