Closing a pipe also waits for the process executing on the pipe to complete.This explains what's going on. If you don't close STDOUT, your process exits immediately when it finishes putting data into the queue. If you do, Perl waits for the more process to terminate (so it can provide an exit status).
If you add a wait after the loop (instead of close STDOUT), the more process runs "correctly". But if you page your way all the way through the file, you deadlock on Perl waiting for more to terminate, and more waiting for more data or end of file to terminate. (Typing <samp>q</samp> to exit more exits both programs, of course).