# 4 GHz, CentOS 7 ( Perl v5.16.3 )

$ perl foo1.pl | wc -l      # Foo::Inbox
duration:  0.441 seconds
   50000

$ perl inbox.pl | wc -l     # MCE::Inbox w/ blocking capability
duration:  0.422 seconds
   50000

$ perl foo2.pl | wc -l      # MCE::Shared->queue
duration:  0.645 seconds
   50000

$ perl foo4.pl | wc -l      # Thread::Queue
duration:  1.544 seconds
   50000