Or another version for this nested parens matching from the camel (3rd edition) which is a little bit easier to understand IMHO. But I'd guess that the recursion makes it slower

$re = qr{
           \(
           (?:
              (?> [^()]+ )    # Non-parens without backtracking
            |
              (??{ $re })     # Group with matching parens
           )*
           \)
        }x;

$text =~ s/$re//g;
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-- Hofmator