Here is a benchmark to show the difference. I added wc for comparison:

    $ time wc -l bigfile
      91420 bigfile

    real    0m0.016s
    user    0m0.010s
    sys     0m0.006s


    $ time perl faq.pl bigfile
    91420

    real    0m0.032s
    user    0m0.027s
    sys     0m0.004s

    $ time perl cody.pl bigfile
    91420

    real    0m0.105s
    user    0m0.098s
    sys     0m0.008s
[download]

Here is the way I usually don't do it, this is twice as slow as the slowest method above:     perl -le 'print $==()=<>' file

--
John.

Update: Added benchmark.