time perl script_sem.pl   | wc -l     # 1.849s OP's example
  time perl script_mutex.pl | wc -l     # 0.803s Ditto, MCE::Mutex
  time perl script_mce.pl   | wc -l     # 0.339s MCE, no chunking
  time perl script_chunk.pl | wc -l     # 0.179s MCE, chunking enabled