Issue #1740 has been updated by Nobuyoshi Nakada.

Status changed from Open to Rejected

Too many backtracks consume a lot of time.
You can use (?>...) to suppress backtracking:
  reg = %r{(?><div\s*class\s*=\s*.entry.*?>.*?<img\b[^<>]*\s+src\s*=\s*.([^\"|\']*).*?>).*?<p\s*class\s*=\s*.date.*?>}im

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http://redmine.ruby-lang.org/issues/show/1740

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