Your regex doesn't backtrack if there is a closing quote, so in this case the possessive quantifier doesn't help here.
I guess that the regex engine optimizes the search by looking for a literal ", and fails immediately if it can't find one. That works the same way in both cases.
Update: to disable this optimization you can use ["'] instead of " (a single char character class doesn't disable it).
In reply to Re: Possessive Quantifiers in Perl 5.10 regexps
by moritz
in thread Possessive Quantifiers in Perl 5.10 regexps
by casiano
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